Lost communication with TCM?

Original problem was hard shifting kind of slamming into second gear added transmission fluid with conditioner seem to help so I added another one and then my radiator went outside problem not sure if its connected thermostat went out changed out both of those. Shortly after that I went to accelerate in my car was stuck in what it seemed like neutral but was still accelerating somewhat but very limited acceleration and it was very high RPMs like five or six RPMs and would not come down unless I let go of the gas pedal that was when I put a computer on it and it said lost communication with TCM so we assumed it was the TCM didn't end up changing that out because we thought it was a sensor that was out. So my accelerator sensor was throwing a code so I changed out my accelerator pedal and now it's saying throttle body issue so I'm also changing that out I opened up the engine and under the intake that I needed new valves because I also had an oil leak but currently in the midst of that but still have lost communication with TCM so I can't communicate with my transmission to find any codes. Where should I look for wiring harness issues for TCM? Could it be something else?