X loves the cold, hates it warm

[Repoman]

I have been battling a particular issue for about 8K miles now and can't figure it out. I searched on here for a similar issue but no luck.

When it is cold outside (below 50 degrees), my X runs almost perfect. It will stumble at idle a few times at start-up and a few times at the beginning of take off from stop, but otherwise it will accelerate and cruise with no stumble and no SES light.

When it is warm outside (between 50 and 70 degrees), more stumbling at idle and take off and an intermitent SES light.

When it is hot outside (over 70 degrees), rediculous stumbling at idle and take off and constant SES light. The hotter it gets outside the worse it gets to the point where the stumbling will shake the entire vehicle constantly and will hamper acceleration to the likes of a really fast bicycler. The only way I can get it to stop is to turn it off and restart it.

I have pulled the codes in hot weather and get the non-specific misfire code. I've been putting off fixing it since it has been so cold but it is about to get warm again and it will be a pain to drive.

I have checked the DISA valve, it's fine. I don't believe I have an intake leak, none seen. I was thinking O2 or MAF because of the effect of outside temperature but I don't like playing part roulette. Anyone heard of this before?