1987 Ram 50 2.6L cuts out on part throttle when cold

[SubGothius]

So I've got almost the opposite problem of that other thread -- mine runs nearly fine when warmed up (maybe a bit of uneven running), but it stumbles randomly and cuts out under part throttle cruising when cold, revs just suddenly drop to idle and won't rev no matter what I do with the pedal, then sometimes just dies outright though that could just be the idle condition as it doesn't idle well when cold and sometimes dies then as well. Sometimes I can drop the clutch while underway to get it running again, but I usually have to turn off the key and restart with a bit of throttle goosing, which is fun while on the road...

Could this still be the coil ballast resistor and/or fuel cutoff solenoid as well? It does tend to run on (dieseling) when I turn off the engine. When I checked the timing, I noticed the timing light seemed weak/sporadic but wasn't sure if that was just my light getting old/acting up. PO replaced the plugs, wires, cap and rotor several years ago (alas, they didn't note the mileage), and I've already tried new plugs.

[geezer101]

The ballast resistor will do it once it's overheated and won't fire until it has cooled sufficiently (once you've experienced it, you'll know the signs) The fuel cut solenoid will do it randomly (usually trying to cross an intersection in an attempt to kill you - had one do that to me, not fun) Maybe the coil is weak or there is something else connected to the ign circuit that is loading the coil up and/or affecting the fuel cut solenoid? Coils last on average 10-15 years max and will cause hard starts, crappy fuel economy and poor acceleration/gear changes. Check the engine tune, make sure your plugs aren't seriously under or overgapped (decreasing the gap by 0.15mm will allow a slightly more aggressive tune) and try experimenting with your timing. The stock tune nerfs most engines and there's a bit of extra performance lurking in there, waiting to be found.

[SubGothius]

Welp, turns out a bad dizzy cap was prolly the culprit. The old one had carbon tracks leading up to one terminal, so replacing that along with the rotor seemed to restore smooth running. Replaced the plug wires as well for good measure (scored a deal on fleabay for a NOS Magnecor set), and had previously replaced the coil and ballast (to no apparent improvement). However, now it's flunking emissions.

[geezer101]

Hmm, what part of the analysis is it failing?

[SubGothius]

See failure specs in the other thread here