!992 4.0 misfire/Backfire in intake

Jeep has been running great then all of a sudden while driving it started running very rough and backfiring in the intake. Tested the fuel pressure, its where it should be both off and running (44 psi engine off and 32 psi running) and no leak down. Changed O2 sensor, cap and rotor. See no vacuum leaks or cracked/disconnected lines. Checked MAP, TPS, CPS, IAC all seem good. Throttle body clean. New bosche 4 port injectors from K-suspension about 2 months ago. New plugs and wires about 2 months ago. #4 and #6 plugs were fouled when I checked them indicating misfires there. Cleaned all plugs checked gaps and replaced. No crack visible on the exhaust manifold. Intake/exhaust gasket looks good around the edges at least. Still have a visible miss on tach, semi rough idle and steady backfire in the intake. A few weeks ago I removed my Catalytic converter and if anything the Jeep has been running better since then until this happened. I did notice a few days before this happened the idle seemed to be a little higher than normal but not sure if that's unrelated. Help please! I'm going insane

Sounds like you either lost a couple lifters or rounded lobes on the cam. Remove valve cover and turn it over and watch rocker action on suspect cylinders.

No cat is a non issue here. Lots of xjs have run many thousands of miles without one in States with no inspections. I plead the 5th.

Possibly it jumped time ?

Unclewolverine said:

Sounds like you either lost a couple lifters or rounded lobes on the cam. Remove valve cover and turn it over and watch rocker action on suspect cylinders.

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Yeah that's what I'm fearing. After messing with it more I can get the backfire to go away around 2200rpm. Also after cleaning all the plugs and replacing I ran it for a while the pulled them again. The #6 plug was fouled, all the rest were fine so I'm assuming that is where my miss is. No codes are showing on the ODBI when i run a check.

Unclewolverine said:

No cat is a non issue here. Lots of xjs have run many thousands of miles without one in States with no inspections. I plead the 5th.

Click to expand...

I figured as much. Thank you for the reply.

Update. Pulled the valve cover. Cylinder 6 exhaust side rocker is super loose and I can press the push rod down with almost no resistance. Blown out lifter?

Dead liter and/or cam lobe.