97 chevy p/u tranie problem

please help, i have a 97 1500 with the L460 trans, in the morning when truck is cold i start out and it shifts fine through all gears and if i dont have to slow down or stop ( not let it drop out of overdrive ) it will go forever, but if i slow down it will drop to third and will not go back into overdrive, if i stop it drops down to first , but when i start going again it shifts HARD to second then goes into default (2 and 3 only) if i shut the truck off and start again it shifts hard to 2 then defaults? flushed and replaced filter and the two shift solnoid , but was no help any ideas? Thanks

A Trans capable scanner should be used to check for stored codes when the problem occurs.

To me, this sounds like a valve body issue that you are loosing pressure when hot. The tranny then goes into limp mode (firmer shifts).

You don't list the mileage; however, the valve body should be removed and checked for wear. The spacer plate could be worn (check ball wear).

Another option is a Transgo kit which addresses some of the 4L60E weaknesses.

//2000CAYukon

thanks for your answer the kit you said is it the shift kit?? Thanks

thanks for your answer the kit you said is it the shift kit?? Thanks

Yes. https://www.700r4l60e.com/store/product.php?productid=369&cat=64&page=1

//2000CAYukon