Hey all. Not sure where to begin on this. I have a 2001 T/A that is an automatic. It has had the cam, intake manifold, and TB all upgraded. In addition, it has a Volant CAI in it. The tune was done by a reputable shop called P-Tuning.

The problem is when I take my foot out of the gas right before the 1-2 shift and it shifts into second, or right after it shifts into second, it will stall, but only when the A/C or defroster is on. If I have the HVAC totally off, it doesn't happen. I've replaced the IAC and it seems to be a bit better, but it still stumbles pretty badly.

To add to this, a couple days ago I got on it, and it downshifted hard, the tires scratched and then it acted like it shifted to 4th. I had to let off, then push the gas again to get it to downshift. It was almost like the torque converter locked up, but it is a pretty big RPM drop, more than what should happen from a stock converter locking up.

P-Tuning adjusted the TB a bit, and that helped, but they also raised the rolling idle, which also helped. Both of those were done before the IAC. The rolling idle was really high, and I was getting 11 MPG just driving around normally. I had them drop that down to just a little above normal. I'm not sure where to go from here, if this is something failing in the engine, or if this is a possible torque converter/trans issue.

As stated this has an automatic, but it has no traction control. Thanks for any help you guys can give!