New transmission in my truck and a few days later I got a diagnostic report and it read a 708.. Two days later my truck shut off while in drive...now it won't start...what could the problem be

When it drives it flutters like it want to cut off...once driven I have to let the truck sit about 20 min so it can start again...took to get a diagnostic and an emission code P0453 control press sensor high input rpm708...what does that mean...that's the issue of my truck status...can u help please once again and thanks for your time and input. I forgot to mention the check engine light is on..also can I please tell me what I need to check out...hopefully to narrow down sum possibilities...thanks