Well not much to go on, but have you checked your thortle adjustment? Prehaps your gas filter? Idea! I have a 82 E150. it sounds like the same thing wrong with it that your has. i noticed it was spiting gas out of the fuel pump. that little hole in the pump is to tell you the pump it broke. i replaced it and now After fighting with push rod.
It went in. Had to tap the key. And now that i have a working fuel pump to rough idoling is gone. runs smoother now.
Hopefully it is a simple fixed. And it isnt going to be a expensive fix.
About where the plug is to read the codes. i believe it is located either under the dash the left of the steering, Or it may be under the hood on the right. Some time Ford puts them in the oddest places.
Hope it helps you.
P.S. Yes i realize a 82 ans 92 are diffrent. but may it helps.