So My turbo grand prix with a fully built 4t65e is getting very hot. It got up to 260*f when i looked at my scan gauage . It has a aftermarket trans cooler but its not mounted in the greatest location. Anyways once it got that hot it wouldnt shift any more and felt like it was slipping slightly. No matter what you do it just keeps climbing no matter how you drive it. You can drive it for 15 mins while the trans is still cool and it shifts perfect and pulls hard. But then it starts to climb. Any one have any ideas? Level is up on the fluid and i have dropped the pan 2 times now and changed the fluid and filter and no diffrence.