My Jeep is an 02 Wrangler 4.0L automatic, with the following modifications: 4" suspension lift, 1" body lift, Curry Industries Ford 9” Front and Rear axles w/ disc brakes, ARB air lockers, and 456 gears. It's not a daily driver and is only driven for fun, currently has about 42,000 miles. I took it out the other day and out of the blue it started to hesitate at about 2800 rpms and the check engine light started to blink. It feels like the engine isn't getting gas and then gets it back again. I checked the codes and got P0204 and P0304. Misfire in cylinder 4. Here's what I've done to try and correct the problem. So far none of this has fixed it.
1. changed out all spark plugs
2. replaced coil rail
3. replaced fuel injector in #4
4. replaced fuel injector plug in and short piece of wire for injector #4 (something had chewed the wire at the injector plug in)
5. added seafoam to fuel tank to clean injectors
When I disconnect the battery the codes will clear and it appears to be fixed until I drive it for 2 or 3 miles and then it's back again.
At this point, I'm stumped. Any suggestions would be greatly appreciated.