2002 Jeep Grand Cherokee - Lurch/Engine Miss

[BRG25]

2002 Jeep Grand Cherokee with the 4.7L.

The Jeep will stumble and bog down under load, especially when going up hills and I'm having trouble pinpointing the cause. Seems to get worse after it warms up. City driving is fine but not highway speeds. I've searched hi and low online and have yet to figure it out. I've read it could be moisture in the transmission, maybe one of the coils going bad, TPS sensor (which I have replaced). Check engine light is on for an evap leak but I don't think that would be the cause? This Jeep is my winter beater and I'm trying to diagnose the problem without throwing parts at it.

Anyone here ever run into this? Thanks.

 

[GA_Boater]

Is the CEL on only for an evap leak? You may have more than one code. Do you have a code reader? Most parts stores will read codes for free.

 

[MTboatguy]

Never mind, I see it is the 4.7

 

[MTboatguy]

Have you checked your O2 sensors and the MAP sensor, in reading around the web, it seems that has been the problem for a lot of vehicles with that engine having the same symptoms.

 

[greenbush future]

Could be a fuel air delivery issue, you did say city driving is fine yes?Filters and fuel pump would be suspects on my list. I would get the sensors replaced too, or are they like $700.00 each? I know they can get costly.

 

[Fishing Dude too]

First problem it is from Toledo, Jeep had a recall over transmitions if I remember right

 

[NYBo]

Go here:

 

[Gyrene]

So, okay at low RPM but boggs at higher RPM?
Cat converter could be plugged. Fuel pump could be going or fuel filter could be clogged.

 

[dolluper]

Hope it wasn't PO420...I'm laughing.....O2's compenstate at low speed ...high speed vac leak o2's can't keep up ....check your high -low fuel trim numbers

 

[MTboatguy]

After dealing with my late 90's jeep for so long, I am betting on the O2 sensors, jeeps do really funny things when those things go bad, on mine if the front one went bad, the car would go into "Limp" mode and would start out in 3 gear until you changed it and put a new one in. But you need to know what codes it is throwing.

 

[Fleetwin]

If you know you have an EVAP issue, that may be your problem. If the system is trying to pull a vacuum on the EVAP system and gets an uncontrolled vacuum leak, that can definetely create a stumble.

 

[BRG25]

Thanks for all the suggestions. These things are such a pain to diagnose. I'll mess with it some more and let you guys know how it goes. Thanks.