u-joint

I had an old YJ that did that. It turned out to be a vacuum hose leak, so I doubt the same thing applies to the JK.

Is there any chance you've let your Jeep sit for an extended period of time? I went on vacation for over a week (close to 2 weeks) and when I came back the JK ran rough as crud until the remainder of my tank was used. Apparently (my guess is that) the ethanol blended gas doesn't have nearly the shelf life of non-ethanol blended gas.

EarlyJk

Then what plugs are good replacements for our 3.8 engines?

Widewing

In the case of this stutter, it's common to the 3.8 and automatic combination. I've been told that it's emission control related. It usually occurs as the engine is warming up and the Jeep is stopped and in Drive. Once the engine is at operating temperature, it will no longer occur. When it occurs, putting the gear lever in neutral unloads the engine the shake stops.

Brashanic

ummm....it likes to do it when it is hot also. Just sayin'

Widewing

It may in your case. However, that's probably a different problem. A misfire throughout the RPM and temperature range is sometimes ignition related, but there are several good candidates for it.

What jeep_n_co describes is emission related, and not necessarily a problem, per se.

kflash

Mine does it occasionally as well. It isn't the plugs - I changed mine to the bosch platinum +4s awhile back.

azrwilkinson

I have this issue as well, chalked off to either the fan coming on or the ac compressor just cycling. Does it more the hotter it is outside. I also experience slight engine knocking. It could be an ignition timing issue in the ECM.

bradtopp

Yes, I think you are talking about a different problem. The OP has a 6-speed. So do I. It happens in mine from time to time, too. It is not specific to an automatic and 3.8 combination. It is specific to the 3.8. As mentioned above I changed my plugs and the overall rough idle was fixed, however the occassional stutter while sitting at a stop light still rears its ugly head every now and again.

Adam3612

Sounds like you have the little gremlin that so many of us have had for a while now. Once in a blue moon my JK will start to shudder when im at a stop almost like its about to quit, rpm's drop, you feel the engine weakening, then all of a sudden its awake again, the odd time it will stall on you. Personally I think its got something to do with the drive by wire throttle on these f'n things (anyone who knows better feel free to chime in), ever since I installed superchips tuning I havent had this issue.

98jeepboy

Guys when I say this I am not being mean. But do a search. Youll find atleast 5 threads on this issue. I have poseted in atleast one if you want to look it up that way. I only say that cause yall are repeating ideas that have already been put out. To save you some time and thought, there are plenty of things listed on the threads. But it is JK thing and nearly 100% of them do it, an most owners dont care or just dont notice it. Its a glitch in the ECU. Something is given it a false read causeing it. Nothing magic, nothing wrong with it, nothing you can do to fix it. Only way you can fix it permantly is a hemi swap. Sorry to be the bad news bear. I learned to live with it in my 07 and 09. Now I have 2010, I know its gonna happen in it. So I will ignore it. I do have idea on a permanent fix other then a hemi swap. but no one will do it. Its a stand alone ECU for the engine.