I just did a tune up, camshaft sensor and trotted position sensor, but still from 1k to about 1400k it almost bogs but doesn't stall or sound like It's about to die and right after 1400k it pulls and sounds healthy, but only in that section of ROM does it hesitate/ bog a bit and just disrupts regular driving (AX-15) unless I'm gettin on it and passing 1-1.4k range... It's not starving for air or struggling for get exhaust out due to high flow cat and fm40... Any input? It really bugs me!

 

increased air flow without increased fuel flow? recipe for lean conditions. This engine is most efficient around 2100 rpms and gets the most oil to the valve train between 2000 and 2500 rpms anyway.

 

I actually have a snorkel, so not super high flow but thats not the problem either whether i have the snorkel hooked up or not...

 

CMP and TPS el cheapo or dealership parts? Are you sure it doesn't happen at the same throttle position?

I'd check these (you could post in OEM tech for better results):

- Air filter
- TPS with an analog multimeter: It should read very close to 0 VDC on the output when the throttle is closed and about 4.5 VDC at WOT. Work the throttle with the multimeter inline, the needle should move SMOOTHLY across the range. The TPS is just a potentiometer, so if you are unable to backprobe it successfully you should be able to take a resistance reading with the engine off. I'm not sure what the numbers are but resistance should be very high at close position and smoothly lower at WOT.
- Fuel pressure at rail: Hook up a gauge at the schraeder valve and work the throttle. My 99 XJ FSM specifies approx 49 PSI (+/-5). It should not go down when you open the throttle.
- Cat inlet vs outlet temperature: Higher temperature out is good and indicates the catalyst is working properly, lower temperature out is bad and indicates a clog.
- Cat for rattling
- Tune up hardware (plugs, wires, cap, rotor)
- MAP sensor (flat black thing on the driver's side of the throttle body) Take it off gently and make sure it's clean.

Doubt it'd be the CPS.

 

even just a high flow muffler increases the amount of air flowing through the motor... a snorkel furthers that actually because it's pulling in cooler, denser air...

 

BWD parts, not super cheap but not expencive... yea any amount of throttle you give it it does it still through those rpms. K&N filter fairly clean, i have a ODB scanner and i couldnt see any problems while looking at real time operational data, fuel pressure testing will be my next step if i can't figure it out, cat it high flow ebay special, not clogged, just did a tune up cap rotor wires plugs, and ill also check the MAP tomorrow...