[monkeyodeath]

Just went through the car and replaced a few deferred things that needed to be done anyway -- built new spark plug wires (used the same ends but they tested good), new cap and rotor. Replaced the CHT with a 2-wire model and did the reference sensors while I was still in there (insulation on those wires was totally gone).

Still have a weird stumbling idle. As the car warms up it gets to the point where it is really hard to start and won't stay running for more than a few seconds.

Was considering replacing the O2 sensor as it's pretty old at this point (actually have a spare Bosch unit I picked up on sale a couple years ago), but these issues are happening at cold startup, which makes me doubt the O2's influence.

Edit: unplugged the O2 and it had no effect.

Really weird as the car was running fine and passed smog very nicely just a few weeks ago.

The car's stumble isn't like a misfire, it's like it's completely dying very briefly before reviving.

When it dies, the fuel pressure seems to very briefly dip, but I can't tell if that's the cause or the engine dying and the pump switching off.

Starting to wonder if it's the fuel pump. Wondering if the stuck-closed FPR was making up for a weak pump by keeping high pressure in the rail. Now that the FPR is acting normal, small fluctuations in the fuel pump's pressure are enough to bog the engine.

Would be a weird fuel pump failure though. Usually just had them quit entirely.