I have a 1991 Ranger XLT 3.0. 244,000 miles.Within the last two weeks, I started having idle issues & erratic rpms at lower speeds. The idle would waiver above & below 1000 rpm. As I reached higher speeds, it would go away. I replaced the plugs, cap, rotor, air filter & fuel filter to be safe. Today, going down the highway, the engine started losing power & caused the truck to start "bucking". I pulled over & could barely keep it running. If i pushed on the gas it would sputter & almost die. I got a tow to the house. I used my code scanner & got #14 & #18. #14 - ECA has detected an intermittent loss of PIP signal during recent operation. *18 - loss of TACH signal to ECA. I replaced the Electronic ignition module, no change. I replaced the coil, coil connector(a pin wouldn't stay in) & plug wires, still no change. I've also pulled out the spout shorting bar plug & it didn't have any effect. The engine was still idling very rough. I will check my timing, but, I'm beginning to think my distributor has gone bad. Anyone have any ideas?
Thanks,
Screamer141

Check your fuel pressure at the shradder valve on the fuel rail. My Ranger had the same problem as you are reporting, and my fuel pressure was 4 PSI when it was supposed to be 40 PSI (fuel injection). I found my fuel filter had a good amount of rust in it when I checked it. I replaced the fuel filter, but my pressure was still at 4 PSI. I knew then that I was going to probably need to change the in-the-tank fuel pump. It's not a fun job, but you got to do what you got to do. Since I went through the trouble to drop the tank, I changed out the whole pump assembly, but the fact was the real culprit was a short piece of hose on the fuel pump assembly. The Ethanol gas had ate it up, causing a split in it. I also opted to change the whole assemply because the whole metal frame of the pump assembly was severly rusted - thanks again Ethonal! This is where all the rust in the filter came from.
Changing the pump assembly restored by Ranger to "like new". If your fuel pressure is OK, than you have a different problem than mine, and you need to look elsewhere. I just know my symptoms were like yours, so I thought I should tell you to make that fuel pressure measurement.