Hello, I just started having a problem with my automatic 4 speed in my 95 Trans Am. It works perfectly fine under normal or even slightly heavy acceleration but once I hit WOT, it wont shift into 2nd gear. The rev limiter kicks in. If I ease off the gas just a hair, it will shift no problem. The car is basically stock with a few bolt ons (cat back exhaust, K N air filter, etc noting crazy). I have a Hypertech tuner installed too but that was 2 years ago and no problems. My mechanic said to try and replace the TPS sensor. I did that and still no luck. Any help would be greatly appreciated.

Thanks in advance!