I have been working on this truck three days.read the wiring diagrams checked voltage grounds.Just went through fuel system today.New plugs wires cap rotor.Runs like a dream for 20 30 minutes then tach drops starts bucking.nail it cleans up runs but below 3000 rpm starts bucking hard tach all over the place.tested coil it reads in limits still got spark and voltage.acts up for ten minutes then smooths out and runs great again starts its cycle over.eec seems to get wet when window leaks.but it does same thing when it dry outside.I open to any suggestions.just bought truck sorting out bugs and it had a bunch.window will be sealed and I about to take out eec check connections and look inside to see if there visable corrosion.anybody can give me a clue I would appreciate it.