For the past 2 days when I start my truck up (94 t4r 3.0 5spd 171k), it sputters and feels like its missing a cylinder. It did the same thing when I bought the thing 2 years ago (30k miles ago) and the passenger rear spark plug was fouled (there was no gap just deposits where the gap was). I put new plugs in (ngk platinums) and a bottle of fuel injecotr cleaner (every other oil change) and life was good. I know what the fix is new plugs but has anyone else had an experience like this or know what is causing it? The damn plugs are expensive. After about a min or two the truck runs ok. I'm getting ready to drive the thing to keywest @ end of nov and don't need to have a prob on the road. Thanks --ROB

 

Well your plugs are being fouled and thats not normal so you have a oil fouling problem (valve seals/guides/rings) or if its not oily then maybe a leaking injector or just bad compression maybe , hard to say , I would do a compression test on it and see if that cyl or cyl's are low which would mean HG, Rings or Valves leaking/bad .
Coolant leakage(bad HG) can cause the same though the fouled plug would not be necessarily black.