Hesitation accelerating at highway speed...

On the last half of a 170 mile round trip the other day, my 96 XJ 4.0 5 speed started to hesitate (and almost stall) while trying to accelerate at highway speeds. It also seemed worse while trying to do that going uphill. That's not a good thing to happen in Atlanta traffic!

It idles fines and accelerates from a stop OK until it hits higher RPM's. Would the vibrations from a long trip knock something loose?

Any ideas on this one?

If it's during higher RPM's it could be a plugged catalytic converter or you could need a tune-up. Was there a check engine light?

Is it throughout the RPM range once you get into higher RPM's? Or does it start doing it at say 3000 and stop at 35-3750 rpms?
If its doing it in a specific RPM range, i would check to make sure you dont have leaky injectors. Mine was doing this, basically causing the engine to run lean. I was even getting a backfire in the intake. Check the o-rings at the injectors... its possible you have a leak there.
Hope that helps.

Hallo. Mine 92 had the same problem. After a long search in the motorbay and renewing all the ignition stuf. I find out, there was condenswater in the fuelsystem. I had running the jeep with almost a empty tank. In the future I will full up the tank when it is very wet weather.

Well, of course the next day, I couldn't get it to happen again. I did a 50 mile round trip to run an errand and it didn't hesitate at all.

I'm wondering if I got a hold of some contaminated gasoline, because I got a few gallons the morning of my troubles.

Oh well. Let's wait and see...

Thanks.