I have a Ford Taurus that dies after it warms up occasionally. Sometimes you can drive it about 20 minutes, shut it off, and when you go to crank it, either it won’t start, or it goes dead and will not restart. After it sits for a while it starts again. This only happens every few weeks and after having it towed to a shop the mechanic could not make it do this and couldn’t find a problem.
I’d try checking the idle air control valve.
When mine went bad, I got some similar types of behavior. It never failed to start, but it certainly struggled sometimes. The valve was crudded up and sticking like mad. If you ran it for a short distance, and the engine was warm, it sometimes struggled. If it was cold, it started fine. When it struggled, it would catch, but the engine would surge back and forth between around 2600 rpm and struggling to keep running.
Basically, if the valve sticks closed, when you’re at idle, there is no air getting to the engine, so it dies. If it works but is just sticky, they car has a hard time controlling its idle accurately.
Thankfully, you can test this by simply removing the valve (VERY easy to get to on the Taurus) and carefully cleaning it (do not soak it in cleaner, but clean off the exposed guts of it without getting cleaner into the electronics side)… if that helps things, then you might get away with just cleaning or you might have to replace the valve. Good news is they aren’t expensive.
Thanks. I’ll try that. I was thinking fuel problem so I replaced the fuel pump relay first b/c it’s cheap. Since it’s an intermittent problem it might take it a while to show up again.
Have you replaced the fuel filter? I had a car with the same symptoms turns out the filter would clog up and the car would stall. If it sat for a while the junk in the filter would settle out and the car would run for a few hours to a few days then clog up again.