I need to know. RPM jumping around getting worse

Ok so here is the deal...
The 2000 Cherokee was running fine for the past like 2 years. About 3 months ago I noticed when I was going up grades on the freeway that it would kick and jump back and fourth a little bit, but it would only do it for a few seconds and it would stop so I never bothered to figure it out. So, 6 months later, its doing it ALL THE TIME!!! Before I though it might have something to do with being in overdrive and climbing hills on the freeway but it does it now even in 3rd when im driving around town. It seems like it might be doing it more with the air conditioning on but I can not be sure on that one. Its annoying and I can see the RPM's jumping up and down feels like im running out of gas basically. I need advice and this sucks. Daily driver is really annoying me.
BTW I searched on this topic and read for an hour and came up with nothing exactly like this. Anyone with the same problemo?

check ignition and wires. ever change the plugs? change your fuel fliter, air filter, clean TB etc. do a tune up if its been 6 years...

skyjackedxj96 said:

check ignition and wires. ever change the plugs? change your fuel fliter, air filter, clean TB etc. do a tune up if its been 6 years...

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Changed all spark plust ~2 months ago. K&N air filter gets cleaned every time after an off road trip (about every 5000 Miles) I have cleaned the throttle body in the last 6 months. The Jeep is very well maintained.

Fuel filter, no. That is a part of the fuel pump and I have never changed it. I dont think that many people with cherokees do.

I've said it before, and I'll say it again - check for a vacuum leak.

Typically, you'll notice a vacuum leak under two conditions - cold engine, or engine under load. With the long sealing surface of the inline six, and the aluminum intake/steel exaust combination, the bolts can literally "unscrew" over time. I check mine once a year, and usually find one that has loosened just a touch.

You don't need to check them in any particular order - but get ALL of them, and USE A TORQUE WRENCH. As I recall, spec is something like 21 pound-feet - I should have it in the Tech Archive section of my site. A 9/16" short socket with inbuilt universal joint comes in REALLY handy on this job, believe me!

5-90

i didnt realize the 2000's didnt have the fuel filter above the driver rear tire. i change mine every 10K. i was having the same symtoms and turned out to be the wires. but your ignition is different

5-90 said:

I've said it before, and I'll say it again - check for a vacuum leak.

Typically, you'll notice a vacuum leak under two conditions - cold engine, or engine under load. With the long sealing surface of the inline six, and the aluminum intake/steel exaust combination, the bolts can literally "unscrew" over time. I check mine once a year, and usually find one that has loosened just a touch.

You don't need to check them in any particular order - but get ALL of them, and USE A TORQUE WRENCH. As I recall, spec is something like 21 pound-feet - I should have it in the Tech Archive section of my site. A 9/16" short socket with inbuilt universal joint comes in REALLY handy on this job, believe me!

5-90

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OK so im checking for a vacuum leak. I will do this but I do not know what bolts you are talking about. Please elaborate.

The bolts that retain the manifolds to the cylinder head.

Since you probably haven't heard this yet, I'll tell you the simple way to check for a vacuum leak - but you must start with a COLD engine!

Get a can of carburettor cleaner. Lift the hood. Start the engine. You've got about three minutes now - spray a "fog" of carb cleaner all around every vacuum line, the intake manifold mounting surface, and the throttle body base. Anywhere you see the fog get drawn in and the idle jumps, you've found a leak. Make a note of it to fix later.

The manifold bolts will be a little easier to reach with the airbox out of the way, and if you go to Sears and get a 9/16" socket with an inbuilt universal joint, it makes it MUCH easier to reach the lower bolts! Trust me on this...

Anymore questions - just ask!

5-90

5-90 said:

The bolts that retain the manifolds to the cylinder head.

Since you probably haven't heard this yet, I'll tell you the simple way to check for a vacuum leak - but you must start with a COLD engine!

Get a can of carburettor cleaner. Lift the hood. Start the engine. You've got about three minutes now - spray a "fog" of carb cleaner all around every vacuum line, the intake manifold mounting surface, and the throttle body base. Anywhere you see the fog get drawn in and the idle jumps, you've found a leak. Make a note of it to fix later.

The manifold bolts will be a little easier to reach with the airbox out of the way, and if you go to Sears and get a 9/16" socket with an inbuilt universal joint, it makes it MUCH easier to reach the lower bolts! Trust me on this...

Anymore questions - just ask!

5-90

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Thank you. I will try this tomorrow or the next day. I will let you know the results.