89 reliant plymouth car stall out

The carburetor may be flooding with gas.Sticking closed choke may also be at fault or both.If you are using fuel with ethanol in it, the carb may be damaged from the fuel.

Have you cycled key to retrieve trouble codes? Do you know how?

yes this is possible ,if the car isn't over heating

Yes, the pick-up coil was a common cause of what you describe.
Drive along and suddenly die, but by the time help arrived it would re-start, and run for a while again, then quit again until it cooled down.

Sounds like vapor lock. This means that fuel is being boiled before it reaches the engine. Check for loose insulation, gas line exposed to exhaust pipe, etc. basically your gas has to remain cool before it gets used by the engine.

If it is fuel injected most likely clogged fuel injectors and your spark plug problem sounds like a oxygen sensor or exhaust sensor.

Possibly a fuel issue, but have the pressure checked before condemning the pump. Is the gas filter good? And the air filter?

It could be an idling issue-idle too low. Check if can be raised, or if idle control motor or valve needs service. Idle should be around 750 rpm, in drive gear, maybe a bit lower, not below 650 rpm, though.

sound like fuel issue, replace fuel filter, check fuel pressure should be 15 psi if fuel pressure okay the automatic speed control not working more likely.the ignition timing could be off also.if you see check engine code scan for fault codes.faulty egr valve cause engine to stall out.

The stalling and stopping sounds like the FUEL FILTER. My 84 Reliant was doing the same thing to me. And as soon as i replaced that... The car ran perfect.

i had this or similar sounding issue with my robin trike, after lots of messing about it was found to be a loose alternator not generating enough charge to keep the battery topped up. I imagine the drive round the block used quite a bit of your battery (30 amps approx just to start it) thats when i got my stalling and sluggish responce, not enough power to fireup the plugs 100% run a volt meter on the alternator and the battery