I have a 1999 Cherokee, 4.0L, 223,000 miles and I experiencing a problem this morning on my way to work.
After driving for 20-25 minutes at highway speed (70+), several times the engine bogged down (loss of power) while attempting to accelerate, to the point of almost stalling. After easing off the gas for a second or two, I could accelerate again. The problem worsened the faster I went and it only happened above 60 mph.
No dash lights came on and all gauges were normal (they didn't move while engine was bogging), but unfortunately I didn't pay close attention to the tach.
Environmental conditions: outside temp, 2 degrees F; 3/4 tank of gas; clear, level, paved roadway.
Once I exited the expressway, the engine operated normally. No hesitation/bogging/loss of power at all, either while driving or at idle.

I have been searching various forums/sites and have found similar problems, but nothing exactly the same and just as many different possible solutions. I'm hoping someone here has a good idea of which direction I should go to try to diagnose this problem. I am not a mechanic, but I can perform basic and some intermediate diagnostic/shop tasks. However, checking fuel pump, vacuum hoses, pressures, etc. is beyond by ability.

Thanks for your help in advance!

 

Can you get it hooked up to see if there are any codes?

 

One of mine did the same thing about a month ago. The converter was the problem. I'm not gonna say how I fixed it or the Cat Police will try to send me to Banned Camp. Let's just say I fixed it for about $10.

 

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Yes, I plan to stop by an auto store on my way home to see if there are any codes, assuming I can make it home under its own power...

 

Turns out it is a bad fuel pump.

 

Closure, Excellent!

 

And how did you find this out?

 

Took it (towed it, really) to my dealership. It took them two days, but they finally got it to stall. They checked the fuel line pressure and it was zero.

 

zero is not enough... thanks for letting us know.