2.3L ('83-'97) Low Rpm and Runs Rough

[Ghost of Progress]

I'm new to the forum, I have a pos 93 2.3l 2wd manual ranger that I have slowly been working on restoring over the past year.

Today I drove through a hefty puddle (not sure if it is related or not) which at the time did not cause any issues other than a drop in voltage, later in the drive the truck started shaking like it was misfiring and idling really rough, I pulled over topped off on fluids and revved it for a bit and the truck stopped idling rough, but still drives rough.

I found out that my egr valve is bad, but was unplugged so I do not think that was my main issue either way I am replacing it tomorrow. So I'm wondering what could cause it to run rough only when not idling

Since I got the truck I replaced the fuel pump, O2 sensor, Coolant temperature sensor, All spark plugs and wires.

 

[SenorNoob]

Fuel filter? (Not enough flow to keep up with a sudden change in demand?)

 

[Onthetrailto]

I would check your fuel pump circuit. Weak voltage to the fuel pump could cause hesitation under load. Had a similar issue on my 93. Wound up being an old fuse that was falling apart. Relays are another common issue.

 

[Ghost of Progress]

I tried switching out the relay but the one I put in seemed to be bad since the engine stalled out, but when I put the old one back in the engine idled properly for about fifteen seconds before dropping back down. I'm going to try to replace the fuel filter today and see where that gets me.

I also cleaned the iac valve with throttle body cleaner which made the truck run properly for a while and then the rpms plummeted again, I did this again same response, so I replaced the valve and this did not fix the problem. So I'm hoping the fuel filter has a better response.

 

[Ghost of Progress]

I would check your fuel pump circuit. Weak voltage to the fuel pump could cause hesitation under load. Had a similar issue on my 93. Wound up being an old fuse that was falling apart. Relays are another common issue.

Update,I checked the relay which tested good, but swapped with a spare anyway with no change, I have replaced the fuel filter, checked the fuel pump and checked the fuel pressure regulator (checked for fuel in the vacuum line and unplugged vacuum line when running)
The first time I unplugged the vacuum line the truck ran correctly, I then tried to recreate it and it ran correctly for five seconds then the rpms plummeted. I am at a complete loss.

Fuel pressure sits at 30, jumps to 40 when I unplug regulator.

 

[Ghost of Progress]

I forgot to add in, after it sat overnight after the original drive back in now idles rough also, I installed a tachometer and it seems to be idling around 400 rpm and when I rev it to 2500rpm it sounds like it is redlining. I Originally thought the tachometer was installed incorrectly, but the few times that it decided to run properly, most recently after towing it back to my house the rpms seemed right with it idling around 800-900 rpm and having actual fluctuation while driving. The rpms dropped when the problem started back (about 5 minutes into the test), and there was a bad smell of gas and no gas leaks seen so I'm assuming I have quite a bit of unburnt fuel.

 

[Ghost of Progress]

I figured out the issue, I replaced the ignition control module after verifying that the misfire didn't follow the plugs and wires, and now it is running properly, no more misfire. I have driven it for a couple days now and it drives better than it ever has before so I definetly had a few other issues I fixed in the process.

So it seems like getting the icm tested at advance auto does not tell whether the icm is good.