I have a 95 2WD 3.0 auto Ranger. I've owned it since around April of last year. The CEL has been on pretty much since. I had Autozone pull the code, which they said was an "auxiliary emissions sensor" and to do a tune up. I did that, but the light stayed on... I just figured it was something with the truck's personality. It has 151,000 miles.
Last weekend I was driving back (~230miles) from helping swap an engine in Tom's car. About 40 miles into my trip, the CEL started flashing. I pulled into the first rest stop and checked to make sure everything was plugged in, listened to the engine from the outside, and figured I'd try to get home with it. As I drove, I noticed the power was definitely down, and that I was getting terrible gas mileage.
When I got back home I took the truck to Autozone again, and found that it was throwing 3 codes. P0174 (bank 2 lean), P0400 (insufficient EGR flow), and that it is missing in cylinders 2&5. So, to try to attempt to correct the misfire, hoping that would cause enough flow for the EGR, and then the PCM would correct its AF ratio, I switched out the plugs and wires.
After swapping out the plugs
and wires (This time with Motorcraft Platinums... not the Bosch POS's which hate Fords, and Duralast/Autozone brand wires), I took it back, just to see if I made any progress... it was then missing in cylinders 2, 5, & 6, along with the same 2 codes. I had attempted to reset the PCM by removing the fuse for a long 2 minutes, before getting the codes read. When I got home, I double checked the plug wires, and realized that I switched a couple of them. I fixed that, and then restarted the truck. It then seemed to idle smoother, but was popping in the muffler, which is a new thing. That was Thursday. I then let the truck sit for the past couple days, since the windchill here is a bit lower than I'd like to really be standing outside staring at my truck scratching my head.
Sunday, I went to take the truck out, and it would turn over, but not start. I sounded like it wanted to a few times, but just never caught. It seemed as I turned it over, the cylinders would fire, but very spontaneously.
I called Ollie and he suggested the DPFE sensor is shot. DPFE is the EGR Valve Solenoid. There is no reason that the truck shouldn't at least run, even if this is bad.
Today, I went and got a new ignition coil pack, since I figured that could be the cause of the misfires. Nope, nothing. Some random guy walked up and started trying to help me out. At least I now had someone to turn the truck over while I checked for spark. Again, nothing. I talked to the guy at Advance, who, going by his parts list, thought maybe it was the ignition control module, so I spent a couple hours tracing the wire harnesses for this little grey box only to find out that its something only the trucks with a distributor have. I finally found some stuff online that points to the crank position sensor. I now have one of those on order, so hopefully I can get the truck running tomorrow.
This comes after I put new tires and shocks all the way around the truck.