Join Date: Aug 2004
Location: South Bay Los Angeles, CA
having the same exact xj, heres my two cents:
1) the 96, 5-spd manual 4x4 is probably tops among xj's to own.
2) bucking like you describe could be few things. try in this order:
replace fuel filter. its a $12 part and 10 minutes of work. you need good fuel volume and pressure for good idle and driveability.
there's a fair chance the tps has a worn out spot in it. how to check very easily: get the motor warmed up and disconnect the TPS connector. the check engine light will come on, but should drive fine. if bucking stops, TPS is worn out and is a normal replacement item around 100-140k miles or so. reconnect it when done.
if it's not the tps....the next up is the idle air motor. this is the most likely suspect with the crazy idle where the idle air motor picksup some engine load when you first let out the clutch in 1st gear. use a torx 15 and remove it, clean all the gunk off it, and re-install. then, if it still bucks, get a decent idle rpm and disconnect the IAC (idle air control motor). drive around . if bucking stops now...then you still have bad carbon residue or a worn out IAC .
look, it should be an easy fix, and you do have a rare, great 4.0 xj. with a high flow muffler/cat/ MSD blaster coil/K&N air filter, some overdue fluid changes/plugs/wire cap rotor...you will have an awesome daily ride. it won't cost much, and is incredibly tough.
odds are also very good that the original fan clutch is worn out ($40) normal wear item as well, and is #1 reason for running too hot above 210'F.
here's the biggest tip of all: stickshift 4.0's are known to shear off the motor mount bolts going in to the engine block on the right side, below the ignition coil....if they are loose, replace them/check them!!! these would be the plate that goes against the block, on each side, just above the oil pan. I sheared all 3 a month ago and only wish someone told me the same to check them, there are postings of 95+ year models (only with stick, around 5% of 4.0's have stick!!) that the bolts vibrate loose and shear off due to the high torque output of these motors. if you feel a lot of vibration in the stick (left to right) while going uphill in 1st gear or 5th down the freeway...YOUR BOLTS are loose, trust me... there's a huge difference in smoothness when the bolts are correct, and much smoother idle/freeway feel.
Newly Painted! Emerald Green '96 XJ 4x4 4.0 HO 5-spd
3" Lift + 31" Tires / D35 TracLok / NP231
Drilled out Stock Airbox / Gauge Cluster Upgrade
Magnaflow Muffler / High-flo Cat / MSD Coil