Can someone enlighten me on how why this might happen. The obd datalink connector connections have been cleaned. Does A2 and A6 have anything in common other than the MFI control module?

The car was purchased not running because of a frozen tensioner and broken timing belt. Car ran well after belt replacement. Also replaced crank position sensor, radio suppression relay, fuel injection relay, fpr, plugs wires, rotor and cap, transmission fluid changed, oil and filter changed. Car started, ran for maybe three blocks, stumbled as I stopped, wouldn't restart for about an hour. I then let it run and it died restarted a few times. I then reved it up to 2500 rpm and the car stumbled and lost maybe 500 rpm but kept running. I then let it idle for a while and turned it off. Now no start after several attempts and No A2 or A6 code. I cleaned the throttle body and it was really gunked up. I didn't remove or move the tps. No fuses are blown.

A few "next" steps would be appreciated. My daughter turned 16 and I was hoping this will make a good buper car for her to venture out in.

Thanks for any advice.