mine is doing the same thing. if i drive with the ac on and give it about half throttle the check engine light comes on and i get p0121 code and it goes into so kind of limp mode and wont downshift if i floor it or anything. its done it 3 times only if i turn on the ac? i've just been pulling the negative off for a few hours and it resets. im suppose to get a new tune soon...

 

hmm. Kinda odd, the way Zippy talked he didnt think they were a linked problem. Odd that yours is doing it.

I havent even had the a/c on in mine.