1991 Pontiac Sunbird stalling

It is a possible fix.

Engine off, With the connector loose from the coolant temp sensor, you can use a jumper wire between the two terminals, that tells the computer that the engine is hot. Drive the vehicle, with it fully warm, if it runs ok, then, I think it is the coolant temp sensor.

I can't guarantee anything, because, I can't see anything from here.

Nice picture, yeah, I'd replace the wiring connector. I still can't rule out the coolant temp sensor?

I've been told before not to post links on my posts. Rock auto . Com has wiring connector for this, you will have to splice the wires. The connector already has the wires embedded, you have to splice wires to existing wires, I believe, 13 or 14 dollars.

I don't know if your local autostore would have that connector or not?

Without putting a scanner on it, I got nothing else. Even at key on engine off, you can get some info. It will tell you engine temp. With a cold engine, the engine temp and outside temp should be close to the same. If it is way different you have a problem. Whether the problem is the computer--wiring or what?

Don't know, got nothing else at the moment.

You could use a fuel pressure gage to check for correct pressure and pressure leak. You cycle the key to build fuel pressure, turn key off, see if pressure holds for a bit. If the pressure drops like a rock, you have a leak.

I still can't rule out the coolant temp sensor? Did you say the sensor was knew?

I'd check for a fuel pressure leak.

As far as the coolant temp sensor, there could be other issues besides the sensor itself, but, I'd check for the correct fuel pressure and pressure leak, first.

If you pull the vacuum line off the fuel pressure regulator, any gas in the line, if so the pressure regulator is faulty.

After you build pressure, just key on, block off the return and pressure lines, if pressure still drops like rock, check the fuel injectors.

I just wanted to add, after you fix it, smell of the oil on the crankcase dipstick. If it smells like gas, change the oil and filter as many times as necessary to get rid of the gas smell.

I'd replace the fuel pressure regular. See how it goes from there.

If engine is flooded it will make for hard start.

Did you change the pressure regulator? If so, maybe that fixed it?