You more than likely have a vacuum leak. Get a couple of cans of brake cleaner spray. Idle the engine as best as it can, then start spraying likely suspected areas. Vacuum clusters, intake.
Now there is one other likely suspect. CAREFULLY--remove the large rubber snorkel between the MAS and the TB. Once it is off, turn it upside down. Look at the accordion folds. Mainly the one at the MAF. I had my 94 acting up. It was a PITA to find the problem. When I swapped out the MAF I noticed the break in the snorkel at the bottom side, closest to the MAF.
Hitting PickaPart and other self-serve junker yards, I pulled every single one I found on first gen Explorers. EVERY single one was broken at the bottom. I used "SHOE GLUE" to repair mine.
Chk it out, see if you have a big-time air leak that the MAF is trying to compensate---
when you go to remove that black snorkel, be easy on it. Loosen the two large hose clamps, carefully work it off the mouth of the TB or MAF. If it's been on there a while it might be stuck enough you can rip a bigger hole in the accordion area at the bottom side.
