Im working on my freinds 98 xj with 160k. The engine starts and idles fine and all the low end power is there but when climbing a hill or on the hiway its much more sluggish than my 01. When in neutral it will redline at 5k rpms just like my xj but when driving it wont go past 3k rpm. The fuel pressure holds at 50psi when idling and at high rpm's and the airfilter and spark plugs are new. Im thinking a clogged cat. Any imput would be greatly appreciated.

 

Clogged cat is a good start. First have you cleaned the throttle body and iac yet?

 

I did give it the seafoam treatment via the throttlebody

 

I would actually remove it and disassemble the iac housing and clean it out. It could be getting held open by crap in there. Seafoam wont clean that up.

 

Something like this http://www.jeepforum.com/forum/f9/cl...topics/1114849

 

I teied cleaning the throttle body and IAC and it seemed to help but was not the cause of the problem. I will try the cat when i replace the muffler and tail pipe.

 

It's probably not down shifting when going up a hill, or punching it when cruising.

 

What size tires/lift does it have?

 

What these two folks before me said. OP, how is it shifting. On flat level can he slam the peddle and have it shift into third to overtake someone. Maybe just the AV cable needs to be adjusted. And don't redline hour jeep in neutral. You never know the condition of the engine. Don't want to throw a rod by accident.

 

Its bone stock and it feels like its shifting properly. And for passing on flat road its good its just that extra kick for hills and hiway that its missing.

 

Ok good next question. Hows the air filter, last tune up, fluids etc

 

We got the jeep about 2 weeks ago, new airfilter, oil, oil filter, changed transmission and T case fluid, spark plugs, water pump, T stat. The cap, rotor and wires have not ben changed. But the wires do not look factory

 

Does it get hot running down the highway? ... clogged cat

 

And the oil looked good when we changed it no shavings or sludge

 

No it runs nice and cool around town and on the highway. And we do get a engine light sometimes and i belive it referes to the o2 sensor after the cat. But i dont remember what exactly the code was