Hello everyone! I have a '93 Ranger XLT with the 2.3L I4 Lima engine and the A4LD automatic trans. I believe I'm having issues with the ECU. I bought the truck from a friend, and the problems it was having were hard starts, running rich at the start (extremely, as in spitting black carbon all over my driveway), rough idle (rpms surging up and down), misfire (no code but the engine shakes horribly and runs a little rough) and generally just running like garbage, also the CEL would come on. HOWEVER, if you let the truck run long enough, once it would warm up for a bit, the engine would give a sputter like it was about to die, then fire right up and start running smoother (still a little rough with misfires and shaking), the CEL would turn off, and it wouldn't extremely rich. So I did the usual tune up, new plugs (I checked the gaps), new coil packs, new spark plug leads, and interestingly enough when I pulled my plugs they were so carbon fouled they were black (not wet so I don't believe any oil is getting into the combustion chamber, I think its carbon fouling). So after some research I discovered that a common issue was that the capacitors were leaking in the ECU, so I pulled the ECU and yep, the caps were shot. So I ordered a reman from Rock Auto and popped it in. Voila! All the issues were gone and it ran great (except slight misfire but plugs were probably fouled)! For about two weeks. After two weeks the symptoms returned. At first I thought I ruined the ECU by not attaching the + lead on the battery first and arcing my wrench to the truck frame, but I checked the caps in it and one was leaking (thanks rock auto), So instead of ordering a new ECU, I bought some new capacitors (same capacitance, higher voltage rating for longer life) off Amazon (Probably my mistake, this is the kit: ) and soldered them in. Solder joints look good not too terrible, and when I popped the ECU in the truck cranked right up and ran great! Then when I went to start it the next day the symptoms returned. I'm at my wits end, and I cant bring the truck anywhere because the trans blew its front seal and I haven't gotten around to replacing it. All help and tips are greatly appreciated. I'll put a list of repairs and symptoms below.

Symptoms:
-hard starts
-running extremely rich
-fuel pump running constantly at Key On Engine OFF
-misfires
-surging RPM
-give it enough time, the engine sputters and starts running better, CEL turns off
-ALSO, OBD1 scanner not able to interface with ECU when truck running rough, but can once symptoms have stopped
-CEL that occurs when truck is running rough is NOT saved in ECUs DTC memory
-for some reason, if the scanner is able to interface with ECU when truck is running rough, CEL code does NOT appear on scanner and the truck magically starts running better.

Repairs:
- New relays for the Engine Compartment Fuse Box
- New Fuses for the Engine Compartment Fuse Box
- New ECU (Had to solder in new Caps)
- New Plugs
- New Spark Leads
- New Coil Packs
- New Fuel Pump + Fuel Filter


Sorry for the long post, but I wanted to give as much information as possible. All help is greatly appreciated.
NOTE: The only reason I'm putting so much work into the truck is that it was pretty well kept, the frame is in great condition, it was owned by some older people previously and it only has 107,000 miles on it. For $1500, I figured it was a great project, but now it's just giving me anger issues.

 

Figured it out. Was a massive vacuum leak and bad injectors :)

 

i having same prob. but i have a 5 speed thought about changing ecu

 

Pull out the PCM/ECU and open it up, you will see 3 barrel/radial capacitors, usually blue, they can leak or fail, under $5 to replace all 3
That's what a "rebuilt" PCM/ECU has, 3 new capacitors

Picture here: Ford EEC-IV
Layouts are different by year but you can see the 3 blue Capacitors

Picture here of one that leaked and pin broke: https://www.corral.net/attachments/dsc00753-jpg.791538/

And you can see the white "specs" on the circuit board, that's from a Clear coat(with white specs, lol) that is sprayed on the circuit board after assembly to make it moisture resistant, just FYI