Will a bad or out of adjustment TPS cause the engine to not start? Was having trouble with car stumbling and hesitating and I got a code 12 and 18(narrow and full range TPS). The stalled while driving, I had to get it towed home and now it won't even start. Still giving the same codes as before.

 

You might've just flooded it possibly when it stalled? Maybe...

I've started multiple cars with bad TPS's or ones even unplugged completely.

 

In order to be completely sure about the functionality of your TPS, you need to check it with a voltmeter at the ECU. Check the voltage range from no pedal to WOT (key on, car not running). You should see smooth ramp up from 1 volt to about 5 volts with no drop offs. With the car fully warmed up and at idle the voltage should be 1.0. On my '91 N/A the positive lead of the voltmeter goes to ECU pin 2F and the negative lead goes to a ground.