Cherokee A: 98 4.0/AW4, 185k miles, stock engine/trans
Cherokee B: 01 4.0/AW4, 150k miles, stock engine/trans

Ok so cherokee A started having an issue where at highway speeds it would stutter for a second every now and then. It would get worse the longer you drove it and the trans would start spitting fluid out around the bell housing. We never figured out what happened and this jeep sat up. The engine was eventually pulled.

Cherokee B was rolled. So Everything (engine/trans/suspension) from Cherokee B was moved over to Cherokee A. This means the 01 coil packs were removed and the distributor from Cherokee A was put in (wiring wouldn't match up otherwise). For 2 weeks Cherokee B (in Cherokee A's body) drove great until it started doing the exact same stuttering thing.

So I replaced the ignition coil, plug wires, rotor, and cap (all originally from Cherokee A). This didn't help. When the stutter happens the RPMs don't even move. I'm going to get a fuel pressure tester and see what it gets but the fuel pump assembly is all new so I don't think its the pump/filter.

If I drive around town it won't do it. It only seems to occur at 60+ mph. So now I'm lost. I don't know what else to check after I do the fuel test.

 

You changed the coil, plug wires, rotor and cap, but have the spark plugs ever been changed? Fuel injectors could be clogged/bad too if they had 185k on them.

If it only happens on the highway then it's probably a load problem, meaning it only happens at higher rpms/engine loads. Most likely fuel or spark problem, or maybe a vacuum leak.

 

Speed sensor in trans, change it.

And....or........TPS.

 

Well the fuel injectors, spark plugs (less than a year old) and anything transmission related were from Cherokee B (the 01) which didn't have any issues. Since it's the same problem the 98 had before I swapped everything I keep thinking it has to be something that wasn't transferred over.

 

OK, regardless, I'll stand by my recommendation and add:

02, bank 1 and 2
and add that you should check grounds and cables....>>>EVERYWHERE and connection to computers.



If it idles well........accelerates well..........strong at WOT........shifts correctly.........drives around town OK.....etc...........
But........has this dead spot at highway speeds..........speed sensor or TPS and could be 02.

 

Mine only did it at cruising speed... was the O2 sensor. No codes (1991 xj)