I have a 2000 Plymouth chrysler 4 cylinder which seems to be having a severe idling problem. It idles rough in neutral but when put in drive or especially reverse it seems to act as if its chugging. About 2 weeks ago put some of that oil bar leak stuff to help close up a rear oil seal leak. (did that first before having to take the transaxle off) But it lessened the leak but didnt stop it. Anyways a week later, it comes up with this idling problem. Changed spark plugs, which had alot of ash buildup (I assume from the specialized additive oil) still, the same problem. Put a spark tester and tested all spark plug lines, all good. Put some injector cleaner in the tank and still the same. Tried looking for a intake leak with carb cleaner and found none visible. But one weird thing is that I put a vacum pump on the EGR valve while running and the engine did not die or stumble when applied. (changed the EGR valve bout 4 months ago and cleaned out the long tube, it was packed with carbon) Anyone here have an idea what the problem could be?
EdwinT