If I recall correctly, the later-model 4T60E transaxles have a single plug from the PCM to the trans, hence preventing you from disconnecting just the TCC solenoid without cutting wires. If it is the TCC then you can have fun tearing up the driver's side and swapping out the solenoid yourself, or give the transaxle a shot of TransTune or TransX, then change the fluid and filter. I'd give the additive a try first, since the two I mentioned are usually the only ones that actually -do- anything...