Yes
Romans 9:1
I speak the truth in Christ—I am not lying, my conscience confirms it through the Holy Spirit
Acts 13:9
Then Saul, who was also called Paul, filled with the Holy Spirit, looked straight at Elymas and said,
Not Sure
1 Corinthians 7:40
Yet in my judgment she is happier if she remains as she is. And I think that I too have the Spirit of God.
Why is Paul not sure?
Right from Saul of Tarsus being converted to faith in Christ, the Holy Spirit was bestowed on him. This is unarguable, as shown here by the words of Ananias reporting God's instructions to deal with this former hater of Christians:
"And Ananias went his way and entered into the house: and putting his hands on him said, 'Brother Saul, the Lord, even Jesus, that appeared unto thee in the way as thou camest, hath sent me, that thou mightest receive thy sight, and be filled with the Holy Ghost" [after which he was baptised.] Acts 9:17 [bold italics mine]
God had also said he would show the now converted Paul the many things he would suffer for his name's sake, as a chosen vessel to bear the Lord's name before Gentiles, kings, and Israelites - vss. 15-16. To his dying day, Paul suffered many things for being faithful to his Lord, dying a martyr's death. So, with those facts established, what could Paul have meant when he said later, "I think that I too have the Holy Spirit"?
The context of that one verse (1 Cor. 7:40) shows Paul addressing other Christians. He was taking them along a line of reasoning about men, women, marriage and remaining unmarried. If any of those considering his instructions disagreed with Paul, they might try to claim that the Holy Spirit in them instructed them differently. Context shows that Paul would not argue about this point (which is not a fundamental gospel message or instruction regarding salvation). He mildly pointed out that if they thought their having the Holy Spirit was significant to understanding the matter, then he too had the Spirit of God. That would, in effect, cancel out a brother's disagreement with him, if based on having the Spirit of God. They both did. But Paul was not out to start a quarrel with brothers on this point. He mildly concluded that matter in his letter before moving on the the much more theologically significant matter of avoiding worshipping idols. Some were in danger of sinning against Christ or, of stumbling brothers with weaker consciences. So, by the start of chapter 9, Paul is more challenging to them, now pressing the matter forcefully:
"Am I not an apostle? Am I not free? Have I not seen Jesus Christ our Lord? Are not ye my work in the Lord? ...the seal of mine apostleship are ye in the Lord... For though I preach the gospel, I have nothing to glory of: for necessity is laid upon me; yea, woe is unto me, if I preach not the gospel!" 1 Cor. 9:1-16 A.V.
Paul could have achieved none of that without the power of the Holy Spirit. So, the answer is, "Yes, he had the Holy Spirit at his conversion, and it was not taken away from him, even if in that one verse he asks a question about that. It is a rhetorical question, the unspoken answer to that one of his being 'We all have the Spirit of God."
Barnes addresses this question directly concerning 1 Cor 7:40 -
And I think also that I have the Spirit of God - Macknight and others suppose that this phrase implies entire certainty; and that Paul means to affirm that in this he was clear that he was under the influence of inspiration. He appeals for the use of the term (δωκῶ dōkō) to Mark 10:32; Luke 8:18; 1 Corinthians 4:9; 1 Corinthians 8:2; 1 Corinthians 11:16; Hebrews 4:1, etc. But the word does not usually express absolute certainty. ... It implies here a belief that Paul was under the influence of the infallible Spirit, and that his advice was such as accorded with the will of God. Perhaps he alludes to the fact that the teachers at Corinth deemed themselves to be under the influence of inspiration, and Paul said that he judged also of himself that he was divinely guided and directed in what he said - "Calvin." And as Paul in this could not be mistaken; as his impression that he was under the influence of that Spirit was, in fact, a claim to divine inspiration, so this advice should be regarded as of divine authority, and as binding on all. This interpretation is further demanded by the circumstances of the case. It was necessary that he should assert divine authority to counteract the teaching of the false instructors in Corinth; and that he should interpose that authority in prescribing rules for the government of the church there in view of the special temptations to which they were exposed.
The other verses quoted by the OP clearly show that Paul was under the influence of the Holy Spirit. Here is another from the same letter to the Corinthians:
1 Cor 14:37 - If anyone considers himself a prophet or spiritual person, let him acknowledge that what I am writing you is the Lord’s command.
Further, since we are also told other things that lead us to believe that Paul definitely had the Spirit of God.
Rom 8:9 - You, however, are controlled not by the flesh, but by the Spirit, if the Spirit of God lives in you. And if anyone does not have the Spirit of Christ, he does not belong to Christ.
All Scripture is God-breathed and is useful for instruction, for conviction, for correction, and for training in righteousness,
Since Paul contributed about half the NT, anyone who suggests that Paul was not Spirit-led is suggesting that much of the NT is not divinely inspired. Peter confirms that Paul wrote Scripture:
2 Peter 3:16 - He [Paul] writes this way in all his letters, speaking in them about such matters. Some parts of his letters are hard to understand, which ignorant and unstable people distort, as they do the rest of the Scriptures, to their own destruction.
First of all, we shall notice that Paul was using a rational tone to discuss various matters in 1 Corinthians, in contrast to 2 Corinthians. He set himself a boundary when interpreting the scripture, as he said in 1 Corinthians 4:6-7 NIV
6 Now, brothers and sisters, I have applied these things to myself and Apollos for your benefit, so that you may learn from us the meaning of the saying, “Do not go beyond what is written.” Then you will not be puffed up in being a follower of one of us over against the other.
7 For who makes you different from anyone else? What do you have that you did not receive? And if you did receive it, why do you boast as though you did not?
From the text, Paul was likely addressing someone was boasting themselves as being more knowledgeable than others of the scripture, as if the knowledge was from their own wisdom and not from God.
Note Paul was answering various questions in a letter, written by the Corinthians (1 Cor 7:1). 1 Corinthians 7:39-40 refers to remarriage of a widow, that the OT has no explicit reference. Therefore Paul wrote with honesty in the beginning of vv40 'In my judgement'
40 In my judgment, she is happier if she stays as she is—and I think that I too have the Spirit of God. (NIV)
Now, does the 2nd half of the verse 'I think that' represent an uncertainty?
Perhaps we need to include two more words 'I think that I too'. The word 'too' indicate Paul was comparing himself with someone else. This 'someone' was likely those people who boast themselves (chapter 4), and might have taught the Corinthians about remarriage, that claimed from the Spirit of God. Paul was claiming his teaching had the Spirit of God as well. Paul for sure knew he had the Spirit of God, he just chose words that he thought was proper at that time.
Why would Paul use a weaker tone in his expression? I would imagine his initial intention was to go soft to the Corinthians when 1 Corinthians was written. In his disappointment to the response, his 2 Corinthians became acute and sharp to the points.
