HELP! P2105 and U0300 codes after custom tune

[plasater]

I recently had PHP do a custom tune 91 performance for me and just installed it last week. It worked great for me until just last night I was driving home and at around 50mph the tranny started slipping out of gear and i freaked out because I knew that was not a good sign because I had that happen to me when my transmission went out and I just replaced it about 6 months ago from the Ford dealership (ouch - big money) So i know that it is NOT the transmission going out. I pulled over and checked the codes and P2105 - throttle actuator control system - forced engine shutdown and U0300 - internal control module software incompatibility. I was pissed (still am) so i returned the truck back to stock thinking that it would fix the problem but the tranny keeps slipping - I know it is NOT the transmission. I've researched as much as I could and can only find that the Throttle Position Sensor might be bad and the throttle body might need to be replaced or the PCM needs a reflash or possibly needs replacing. However, this happened way too close to the install of the custom tune so I call BS. Can anyone help me? I know PHP takes forever to try and respond. I've already tried e-mailing and calling. I don't mind replacing the throttle body and throttle position sensor if thats really the case but I don't want to start throwing money and trying a trial by error fix cuz i might be in 1500 or more after i'm done. Thanks.