I've been chasing this down for a while now, incredibly annoying.

I'm going to test all my electrical and pressure test my fuel but from this and others I'd say its probably fuel pump too.

 

Just an Update! I've driven my jeep a little over 1,000 miles and no problems what so ever after replacing the fuel pump.

 

I think I need to bite the bullet and just get a new pump

 

 

The problem is I lose speed when running my air conditioner.When it's of my car runs fine. Can you help.

 

I had a similar problem, thought it was the shift and torque converter solenods. I drained what trans fluid that was in the pan, put about 4 quarts of new in and some Trans-x addative. Drove it like that for a day and then drained what was in the pan and replaced with new. Overall I drained and replaced about 2 gallons of Dex/Merc which allowed the trans and torque converter to function properly. The old dirty fluid seemed to be my issue.

 

That post was from two years ago!

 

Yes I know however during my Google search to try and help me figure out my similar issue this OLD thread came up. My post was meant to help others that found this OLD thread while searching as I did for things to try to fix the issues they are having.

 

Yeah, I was just giving you a little ribbing , not flaming you. Lol.

It's a 4 page post from 2011 about fuel pumps and the associated wiring that was resolved with a new pump. Then another guy revived it in 2013 with an AC issue and you again in 2015 for a trans issue. Again NOT flaming you, just gentle ribbing.

 

Hi --

My 99 Xj/4.0 L acted 'funny' a few times, under load usually, where it was running fine then just real quick like stumbled then caught, stumbled then caught but then ran fine. It would happen at random times, but usually just happened a few times over a few days.

Until I replaced my muffler and tailpipe.

I jumped in to hear my sweet new muffler, and nothing. It cranked but no start. What tha? I pulled a plug wire .. no spark. Huh?

Then I noticed that my fuel and volts gauge were not working with the key on. AHA! Computer is 'asleep' -- meaning no spark. Asleep why? This is usually a problem on the 5 volt power bus to the sensors. I started pulling sensors one by one while monitoring the 5 volt line (you could simply have someone watch your fuel/volt gauges with key on) -- and when I pulled the CPS (crank position sensor) plug out .. BAM! Computer came back to life by supplying 5 volts to the bus. Plugged CPS plug back in. BAM! No more 5 volt line.

Checked the CPS for shorts. It was shorted. Replaced it (nasty/stupid place to get at) and the Jeep fired up instantly. The intermittent stumble is also gone, and has stayed gone.

So it appears to me the CPS was going bad intermittently, and momentarily, until it decided to short out permanently. Cheap little Hall Effect Sensor had warned me it was going to fail first, and had the courtesy of failing while it was parked in my garage ... rather than out in the boonies.

So if you can't find your momentary loss of power problem, swap out that CPS. My momentary stumble is gone now, after I changed the CPS. Just sayin' ...

 

Wow! Lazarus would be envious of this thread. Seriously, it's good to know you fixed the issue though.

 

I have a '99 Jeep Cherokee Classic. It has problems mostly when it warms up because in the morning when it is cool there are no problems but as the day progresses and I drive it longer it begins to momentarily stall and the check engine light flashes on and then off. The car never completely cuts off it just stutters and drops the mph gauge and then picks back up. I am debating whether it is a lost cause now or not. If you have any insight on this problem it would be a big help. Thanks in advance!

 

Fuel filter

 

I had the exact same problem.
I had the spark plugs changed out, that didn’t help.

then I put an Injector Cleaner in (bought it from Chevron store)put it in my tank and filled up with 91 Octane from Chevron.
I had just over a quarter tank when I did this. I usually use 87 (regular) fuel.

I didn’t think it would work at all but was worth a try.
at first it was still doing it.
then after a few miles it started to get better.
then after 20 miles, it was gone.

Your welcome!!