Archived Transmission Down shifting

[CMorrow]

While cruising along in third gear my Trany will suddenly down shift into 2nd. I've got a aftermarket Valve-body and TCC. I'm running Amsoil with lube guard. It seems to only occur after the Trany Temp comes up to operating range. I just replaced the Trany temp sensor and cleaned up the TPS about a month ago. Any ideas whats causing this?

 

[Extreme1]

I'll start with the basics: Is the TV (throttle valve) cable adjusted right?



You're checking the fluid level with the trans warmed up?