91 Explorer stalls/runs rough at idle

[Petersonde]

I have a 91 Explorer with the 4.0L V6. Throttle body injection. It just recently lost power and now after it's started, it idles up smoothly, then as the idle drops it runs as if it's only running on 3 cylinders, and dies. It restarts easily but falls into the same problem.

If I keep the RPMs up, it stays alive but still runs extremely rough. I had found some vacum lines that have fallen against the manifold and melted. Those have been replaced. Plugs/Wires have been replaced.

Any assistance is greatly appreciated!.

[splatmike]

I have a similar problem with my 92 Ford Explorer 4.0L . I bought it a few months ago. (Was running OK but didn't have much power). I noticed one day that I had a spark plug wiggling in the block. I then did two things. 1st - I replaced all 6 plugs with AC Delco's. The other 5 plugs could be turned out by hand. I first gapped them at .045 . I then changed the serpentine belt and routed it correctly. (On the pulley on the lower passenger side, they had routed it on the wrong side). The Explorer, in the morning, would start fine - idle up then start relaxing. Would start sounding like 3 cylinders were only firing then die if gas was not applied at this point. With a little more drag on the motor from being in gear, just made it worse. You would have to work both the brake and gas just to get it out to the street. Then it would seem to run fine for seven blocks. But when I hit a stoplight, it died. After it warmed up a little, it would seem to run, idle like it should. I then gapped the plugs to .054 . Same problems. On the highway, the CEL would be on about 1/2 the time but would seem to run OK. I noticed a small vacuum leak, on a line where it entered the (big round thingabob) above where the master cylinder is attached. I sealed the grommet where this vacumm hose entered the big round thingabob). It did seem to run a little better. But the problem still exists. I have pulled and checked all the new plugs for cracks, made sure all boots were on good, cleaned my MAF with brake cleaner, .....????..... Any ideas ??
Thanks
Nebraska

[Petersonde]

Turned out I had two separate problems. First, the Throttle Position Sensor wasn't working. It was causing the "engine dying" problem. The second part was the coil pack. Turns out I only had 3 ports firing. Cost for the coil pack was $72 @ Checker. The TPS was another $50.

Runs like a champ now.