Did you change a head gasket or a valve cover gasket? The reason I ask that question is you could have an intake plenum gasket leak. It's on the bottom of the manifold.

 

Assume you have done the basics, spark, fuel pressure test>?

 

What are you comparing it to that makes it seem to lack power? When brand new, these engines only made 220 hp in a body that weighs almost 5000#. Put a couple hundred thousand miles on it and you may be in the 150-160 hp range.

Cylinder leakdown test along with the above will tell you more than just cutting out and replacing parts.

 

Come on guy! The 5.2 limited only weighs 4053 lbs.

 

Shipping weight, curb weight, gross weight, or reality weight after being driven for 22 years?

Put a tank of gas in it - 150#, a couple of adults in it - 400#, a couple of kids or another buddy - 150#, some gear for fun - 60-80#, and 26 years worth of accumulated dirt, crud, grime, and debris that can't be easily washed off because its packed in frame rails or on top of skid plates where you can't get to it - 20# and you're suddenly knocking on the door of 5k or more with an engine that may have 200k+ on the clock and be down 20-50 psi in the cylinders. Compare that to a trip around the block in your buddy's late model WRX and suddenly the Jeep feels like a blob that can't get out of its own way.

I love my Jeeps, but they certainly aren't hot rods.

You question about the head vs valve cover gasket certainly is relevant and I hope we get an answer on it. I don't see where any of the OPs listed work would make it run better than previously, but some of it could certainly make it run worse if other things were not put back together correctly or other things disturbed or broken in the process.

 

Whats the mileage? How old are the o2 sensors? When was its last tuneup? If it needs a tuneup, check the plugs when you pull them for signs of fouling, running lean, etc.. Whats the fuel pressure? A compression test is a good idea regardless, as is a leakdown test. Replacing parts wont do much if the engine itself is old and tired. Refreshing the engine grounds is a good idea as well.

 

I'm more inclined to suspect the converters. Try a bottle of Mr Gasket Cataclean in the fuel tank. It was like a shot of adrenaline for my 4.0. Find it on Amazon.

 

Says he cut the cat out. No change.

 

have you looked at the breather cap located on the valve cover check to see if it is clogged mine had same problem , cleaned breather engine ran fine no loss of power.

 

Might be waiting a while for an answer, 4 year old post

 

hi
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Assume you've checked the essentials, such as the spark and fuel pressure.