I've got a 95 ranger with the 4 banger. Sometimes it idles rough and when you are just trying to keep speed (not hard accelerating or decelerating) it lugs down ( bucks like a mule is more like it). The check engine light is on, but I don't have a code puller for this model. Does anyone have any ideas other than normal tume up procedures(plugs,filters etc already done). Thanks.

I have had this problem with vacume leaks before! Sorry not much help.

what's the fuel pressure like?? Are the o2's working correctly?? There could be a lot of things to look for but these are a start.
Are all the injectors clean. Try unplugging them one at a time and see if that makes any difference. Are all the plugs firing?? Dist cap etc all clean. Is the dist advancing ? (not likely but could be the problem) Does this occur only when cold, only when hot or all the time??

You've got to get those codes read!!

My best guess would be the EGR valve is carbon'd and sticks open sometimes. Remove it and see.