97 2.5l tj ax5 4.10 graers 2.5" lift and 31" at tires.
Greetings, I'm a first time poster and also a master mechanic. I have owned the Jeep for 6 years, last year the engine lost oil pressure and I got a used rebuilt motor with only 1000 miles out of a 97 tj that got t boned a week after the engine was installed. After about 6 months of driving around the engine developed a miss on cylinder 1 I traced it down to a Crack in the intake runner for that cylinder and changed the the head with a rebuilt O'Reilly head for 300 bucks plus bolts and gaskets.
The problem I have had with it all along even with the original engine is a rough idle slow Rev up and slight miss under heavy load and also pops on decel in gear out of the exhaust and also If i do a throttle snap in neutral it pops from the exhaust . I have replaced the muffler and cat, the front 02 sensor, cap, rotor, plugs, wires, coil, distributor, injector pig tails, head, exhaust manifold, lifters, fuel pump module, engine mounts, and radiator. Most of these parts were old and needed to be replaced I wasn't trying to fix the issues with them. I checked the timing chain it is tight and on time, distributor is on time, checked all the sensor readings and all seem within spec, fuel trims are 3% st and 6%lt at idle cruse it's closer to 0% for both and wot it is 0% (I live in Mesa AZ and it's hot as hell and the summer gas sucks here) I think the alcohol content has something to do with the trims being slightly positive. With a vacuum gauge hooked up at idle it is about 19" at 1300 feet above sea level but the needle vibrates about 1 to 2 inches at idle some times especially with the a/c on. at cruse it vibrates about a half an inch of vacuum. Checked exhaust back pressure and it's .5 psi at idle and about 1 to 2 psi at 2500rpm. Also checked the battery and charging system and at 110° ambiance air temp I'm charging at 13.8v and the battery is strong when tested also.
This is just driving me nuts any ideas that might help would be awesome! If any more info is needed please let me know?