[monkeyodeath]

Trying to track down an issue w/ my '86 (3.2).

More than a year ago, I started to have a very sporadic engine issue. The engine would very briefly die and then immediately come back.

This would only happen at really low speeds, like pulling away at a stop like or accelerating in 2nd gear. Never really happened when pulling hard at higher speeds.

I also noticed that the engine would always start immediately after I turned the key, even if it had been sitting for a few days. Sometimes, I'd even hear a brief lugging/pinging sound, as if was starting so quickly the ignition wasn't keeping up. Unexpected and a bit odd for a 34 year old car.

Last week, the car became difficult to start -- would crank to life immediately and die just as quickly.

Did some research and it seemed very likely that the FPR was stuck closed, so I replaced that.

The change did seem to have some effect - the car starts more normally now, after a few cranks of the starter. But now I have a stumbling idle -- every couple minutes, the engine speed will drop briefly, then come back to life, revving up a little bit before settling back to idle speed.

I haven't driven it yet to see if the stumble persists at low speeds -- a little afraid of getting stranded somewhere.

Fuel pressure tests within bounds, and I notice that when the engine dies, the fuel pressure does not really fluctuate -- leading me to believe it's not a fuel issue or an issue with the DME Relay (which is a new Focus 9 unit).

Also, the ICV buzzes and I notice that the idle speed ticks up briefly after the car dies -- indicating that the ICV is trying to raise the idle speed when it senses it dropping. So I feel like the ICV is okay.

Haven't done a full smoke test on the intake yet but did probe around a bit with a can of carb cleaner and didn't find anything. Would seem odd to me that an intake leak would only sporadically affect the engine while sitting still.

Back when I was trying to diagnose the no-start issue, I tried both disconnecting the CHT and jumpering it, and neither seemed to make a difference. I do have the single-wire version though, so I just bought a 2-wire version and plan to install it soon.

I'll also add that I passed a smog test a couple weeks ago with pretty good numbers, so I don't think something is seriously out of whack.

Any thoughts? Ignition problem? Weak coil? Just not sure how to test such a sporadic thing. I know my ignition wires are probably due for replacement, but would that cause an issue like this? Trying to avoid tossing parts at it.

Apologies for being so verbose, but figured adding all the details might help solve the mystery.