Morbid

iTrader: (34)

When cruising at 60-65mph and I floor it, it'll downshift and pull hard up until it shifts. When it shifts, it'll drop the rpm's to about 4500 or so and stay there until you take your foot out of it. Afterwards, the transmission shifts really hard at partial throttle on the 1-2 and 2-3 shift. 3-4 feels a bit harder too, but it's hard to tell. The only way to fix it is to shut the car off for 15 minutes.

Would the P0123 cause this or is my transmission to blame?

EDIT: The car still has the stock converter and the only modifications involving the transmission are a transmission cooler and tuning (shift points, torque management, etc.)

performabuilt

iTrader: (25)

po123 is the TPS throttle positions sensor and certainly could cause all the above and more

Morbid

iTrader: (34)

Thanks for the reply, I'll make sure that I put the TPS back on correctly. If all else fails, I'll just buy a new TPS.

I was hoping it was the TPS and not my transmission.

performabuilt

iTrader: (25)

Sounds like its your problem so that should fix you up