1980 Toyota Cressida
All stock 4ME engine.
Been struggling with a strange issue for a few weeks now. Car starts up and runs great until the engine is at normal temp. Then it dies. It doesn't struggle or cough. It just cuts off and dies. If i let it sit for an hour or so, it starts back up again until it gets warm.
This issue just appeared one day when i was at a drive through restaurant. There were no warning signs. No maintenance or repairs prior.
Here's what i've checked so far:
No cracks in any hoses anywhere. Removed hoses to make sure nothing is blocking when they are expanding/contracting.
Air filter is like new. Nothing clogged anywhere. Removed Air Meter and was sure that it "clicks" when the switch is opened and closed inside. No cracks in Air Chamber. Removed and inspected the Air Valve (on the intake manifold). Made sure the thermostatic switch opens and closes according to temperature. Tested for proper resistance on electrical switch here.
Tested to make sure that all emissions associated valves open and close when they are supposed to. None of them appear to be leaking at all. EGR Valves are also functioning according to the repair manual.
Tested Ignition Coil for proper resistance on both primary and secondary terminals. Replaced coil just for the heck of it, however it did not change car's behavior. Ignition Igniter/Amplifier/Module was tested for 13.5 volts during operation. No cracks or disfiguration in the Rotor or Distributor Cap. Checked for proper resistance on the Distributor (electronic). All associated wires appear fine. Tested for spark when cranking. Sparks fine when hot and cold...even after the car dies, i still get a good spark. Started car when cold and blew a hair drier to heat up the Coil and Module. They became much hotter than when car is operational, and this did not cause the car to die.
Checked for proper resistance at Thermo Sensor on thermostat housing. Removed radiator cap to relieve pressure. Coolant in radiator will be cool to the touch, however car will not start until the engine block area cools down sufficiently. Checked Cold Start Switch for proper resistance.
I'm at a loss for what else to check. This problem definitely sounds electrical/ignition related, but i don't know where to look.
I'd greatly appreciate any suggestions or advice. I'll try anything at this point. My Cressida isn't my main source of transportation, so i'm in no hurry...but it's a beautiful car and i want to get it back on the road now that the weather is nice.