Im lost guys I got new o2 sensor cap rotor coil plugs those 2 sensors by the TB a new Cat motor has maybe 80k or less on it it has been rebuilt I cant find a vacuum leak so heres the deal it backfires when at idel an when I get on the gas the bottom end before I switch gears it bogges down oh yeah im running the Banks headers I been told it maybe a burnt or bent valve I ran the bigbottel of lucus gas stuff for a week it got a little better

 

just to check the obvious, plug wires are on right and in the right order? Timing chain hasn't stretched, rotor is still syncronized to TDC?

 

What plugs and Gap?

Check the cap it may be defective I have run across a number of them with my 2.5

Is the air temp sensor in the # 3 intake port I think it matters

It sounds like a manifold leak to me

Throttle body is clean?

I find it very weird that so many people with the 2.5 cant get it running perfect I have never had any problems at all.

 

Are you running a 4.0 Jeep throttle body? Did you move all the sensors from the 2.5 TB to the 4.0 it matters.

My 2.5 loves the bosch fine wire iridium - spark plugs with a bit wider gap than stock

 

Ok I changed the coolent sensor an it toned down its not as bad my plug gap is set to the manufacturer settings I also use the champion plugs they suggest ffrom the book they sell at autozone n pepboys the plugs are pretty new but recheck em