jeep bucks accelerating under load

hello everyone, new to this forum.

Can't figure this out. When I accelerate under moderate to heavy load when I hit a certain RPM the engine starts to chug and buck like fuel is being cut off. I have noticed that this happens at different RPMs depending on the abient temp. The warmer the ambient air the lower the RPM that this begins. When the ambient air is 60ish or lower this happens at around 3000 RPM, at 65-72 degrees this happens around 2200 RPM and 75ish and up to 78 degrees it starts at 1800 RPM. The ambient temp has not gotten above upper 78 here yet. I am affraid that once it hits 90 deg then it won't run at all. The TV cable looks good, no excessive play in the cable. I replaced the fuel filter and did a fuel pressure test. Fuel pressure was at 35psi. Ran a bottle of Lucas cleaner in the last tank of gas. Checked the small tiny hose on the bottom of the MAP and it was in good shape. I disconected the MAP and still having problems. Maybe a vaccum leak some where and there is too much air being sucked in? What else could it be? :confused:

check engine is on ?do you try to have the fault code? if you have a p0720 code its output shaft speed sensor cost around 20$ or its maybe other things have your fault codes before
BOB

Check your plug wires, 10k ohms/foot. New or old they act this way when failing.

Chrysler had an issue with the catalytic converters in that year; if you hear yours rattling then the material inside may have broken loose, blocking the exhaust flow.


There is an extended warranty on 96 and up,

http://www.automotiveforums.com/vbulletin/showthread.php?t=933078

so if yours is a late 05 it may qualify.