1991 ford explorer idles rough.

Question

motor idles rough after first start up and after reaching operating temp

Answer 1

start with seafoam. In the tank and in the crank case.

Answer 2

what motor do you have in it? If it's the 302 EFI check the EGR valve with some flamable silcone lubricant with the straw nozze and spray right in the middle of the EGR valve. If it revs up that's the cause. And if it's the 302 EFI also take the same spray and there is a cross over tube on the back of each head that link togethere with  the catylytic prewarming hoses leading from there to the relay switch with the rubber hoses attatched to it. Spray both sides and the bolt where the tubes  are bolted in the back of the heads and if you get a surge then you've found where the vacuum leak is (these are the two major causes of your symptoms due to bad hoses or the pipes between the heads rusting out. If it's right at where the bolts are for each side of the cross over tube on the back side of the heads. Un bolt them pull the whole assembly out along with the so called preheating lines to the catylytic converter which most likely by now are doing nothing anyhow. Then if you have access to a torch with at least MAP gas for a tank you can cut each side of the pipes after where the pipe goes into the fittings that you unbolted to get the assembly out and hack saw them semi close the the block where the bolt goes through but not too close. Heat each one good and hot with your torch and if you can do any braizing with flux. pinch the tubes together then hammer them tight as you can so less braizing and then lay a good bead of braize over the smashed ends and the whole fix will cost you nothing but time of your own. No out of pocket expenses at all. YOu can buy the plugs to bolt on to the holes left in the heads too buy it's cost free and will last for ever if you follow the steps above. Good luck. Had to do it to mine recently cuz i couldn't stand the whistling anymore and took me like fifteen minutes to complete the whole job. Good luck.