Got a question, anyone know what might be causing theese symptoms? I put a new 4cyl engine in my 97TJ, when I first started it up it was fine, now it takes just a bit longer to actually start, then it runs for about 30 second then sounds like it running on three cylinder, you give it gas it goes away an d runs fine after that. It only does it when it hasent been started for a couple hours or in the cold state. The fuel sat for about 6 month without a addidtive, but its been about six month of it running and still does it. Any help would be appreciated.