2006 Jeep Liberty

Engine Performance problem
2006 Jeep Liberty 6 cyl Four Wheel Drive Automatic 47770 miles

i have a 2006 jeep liberty. It only has 47770 miles on it. Recently ive noticed whenever im going uphill or under stress ( usually around 60mph) the engine jerks/missfires/hiccups about every 6 seconds or so until im back on flat roads or slow down. Ive changed the plugs already with bosch platinums but that didnt work. I have been told by several shops it could be the coil pack, fuel filter, air condidtioner draining my power, or a transmission slipping problem. The engine light has never been on and the scanner at advance auto parts and a local shop didnt show up anything wrong. If the jeep has a missfire, why dont it show up on the scanner or trigger the check engine light? Now whenever im on level ground and normal driving conditions the jeep runs flawlessly even with the a/c on. Should I replace the 6 coil packs? Ive changed the fuel filter also. What else would be the likely candidate for causing this? Idle is smooth, even when cold. Any ideas?

3.7l v6
air conditioned
automatic trans
September 1, 2009.

I wouldn't recommend replacing all of the coil packs. That will get expensive. Run the vehicle until a code is set. If this only happens for a short time, the computer may not be picking up on it. As it gets worse, it will eventually pick up a misfire and tell you what cylender so you are not replacing all of the coils.

Problem was solved. Turned out after replacing the spark plugs, coils, checking for vac leaks, it was a faulty/failing fuel pump. Too bad the one that fits my jeep is still a dealer item @ $517.00. Ouch!

Im happy to say now that my jeep never ran better. Im so pleased, even if it did cost a small fortune.

Thanks for all the help! : -)

Sep 18, 2009.
I'm glad you got it fixed. Let us know if you have questions in the future.