I've read a lot of posts, but too many other variables involved in those.

Here's the deal...neighbor bought it used...some 67k on it. 4cyl, Automatic trans.

Runs just great, but it shuts off at random times. Doesn't matter if the weather is cold/warm, or if the engine is cold/warm. Sometimes won't restart for half an hour, sometimes right away. Ignition switch doesn't seem to be sensitive to harsh jiggling, the main relay is probably ruled out since the pump runs when keyed to "run" after it dies. Ignitor/coil issue?

Any solid ideas or trouble shooting suggestion appreciated. I don't want to spend too much time on this dog since the jackass used car dealer he bought it from should be helping him. But...he is neighbor.

 

Although you've given some hints, I'd ask for a little more.

When this happens, does everything shut off, or just the engine that quits? When it does quit, is it sudden, like someone turned off a switch; or does it slowly die?

Sudden shut off:
If everything shuts off (lights, Radio etc), it would still point at the Ignition Switch.
If it's basically the engine, it would point to (Yes) the main relay*, or the ignition Ignitor

Get me those answers and we can proceed furthur.

P

* The main relay is actually Two (2) relays in one. The one you're aware of (Fuel Power to pump), but also power feed for the ECM (Engine Control Module). Failure of either side will cause the engine to quit.