Intermittent stumbling and stalling at idle. Running out of ideas.

Scout425

Member
Joined
Nov 22, 2018
Messages
50
Location
Fairbanks, AK
I'm at a loss of where to go next. Hoping someone on here can help out so I don't have to let some stranger's booger hooks touch my Jeep. Hopefully I've overlooked something simple and you guys can slap me and help me realize my expensive mistake. On the bright side, all these new parts are making me more comfortable with relying on the Jeep in Alaska next year.

2006 LJ
6 Spd Manual
~150,000mi

Symptoms:
Jeep will intermittently stumble and catch itself most of the time while idling. Some days are better than others but I'm hard pressed to make it 24 hours without this happening. I've had it happen when cold after start up in the drive way, but typically it happens at stop lights after reaching operating temp. To be fair, I also sit at idle at stop lights far longer than I do in my driveway. Also, it has not done it in a few weeks, but the Jeep used to stall without warning while coasting in neutral towards one particular stop sign (my nemesis for weeks). No CEL or codes on dash or OBDII reader. Occasionally the CEL will quickly flash (similar to a short) while it's stumbling, then goes out. I also have a very slightly rough idle. This may be due to my mistake when reinstalling the OPDA after replacing my oil pump. Looking for a shop to check.

Steps taken so far (parts/money thrown at problem): Not all parts are related to this problem but will list for complete picture.
IAC Cleaned: No improvement. Found O-ring to be damaged.
IAC Replaced w/ MOPAR unit: No improvement
Coil Pack replaced w/ MOPAR unit: No improvement
TPS Sensor replaced w/ MOPAR unit: No improvement
Battery replace w/ Odyssey Extreme
Spark plugs replaced with Autolite XP985 and gapped to .040

Smoke test and TB cleaner spraying conducted:
Vacuum tubes/check valves from side of manifold to vacuum box replaced w/ MOPAR
Vacuum tube from top of manifold to CCV replaced w/ MOPAR
Slight leak at throttle body valve. I've been told this is normal🤷‍♂️
No additional leaks founds.

Delphi fuel pump: bad anti-drain back valve
Replaced with Bosch 67756 (5161335AE)

Water leaking from exhaust connection above skid plate
I guess this connection came loose after I removed the exhaust to drop my oil pan. Need to quit being lazy and tighten it. I cant imagine that this would be my issue though.

If you're still here, thanks and sorry for the long write up. Didn't want to just post "stuffs all messed up. Figure it out" with no information.
 
I'm at a loss of where to go next. Hoping someone on here can help out so I don't have to let some stranger's booger hooks touch my Jeep. Hopefully I've overlooked something simple and you guys can slap me and help me realize my expensive mistake. On the bright side, all these new parts are making me more comfortable with relying on the Jeep in Alaska next year.

2006 LJ
6 Spd Manual
~150,000mi

Symptoms:
Jeep will intermittently stumble and catch itself most of the time while idling. Some days are better than others but I'm hard pressed to make it 24 hours without this happening. I've had it happen when cold after start up in the drive way, but typically it happens at stop lights after reaching operating temp. To be fair, I also sit at idle at stop lights far longer than I do in my driveway. Also, it has not done it in a few weeks, but the Jeep used to stall without warning while coasting in neutral towards one particular stop sign (my nemesis for weeks). No CEL or codes on dash or OBDII reader. Occasionally the CEL will quickly flash (similar to a short) while it's stumbling, then goes out. I also have a very slightly rough idle. This may be due to my mistake when reinstalling the OPDA after replacing my oil pump. Looking for a shop to check.

Steps taken so far (parts/money thrown at problem): Not all parts are related to this problem but will list for complete picture.
IAC Cleaned: No improvement. Found O-ring to be damaged.
IAC Replaced w/ MOPAR unit: No improvement
Coil Pack replaced w/ MOPAR unit: No improvement
TPS Sensor replaced w/ MOPAR unit: No improvement
Battery replace w/ Odyssey Extreme
Spark plugs replaced with Autolite XP985 and gapped to .040

Smoke test and TB cleaner spraying conducted:
Vacuum tubes/check valves from side of manifold to vacuum box replaced w/ MOPAR
Vacuum tube from top of manifold to CCV replaced w/ MOPAR
Slight leak at throttle body valve. I've been told this is normal🤷‍♂️
No additional leaks founds.

Delphi fuel pump: bad anti-drain back valve
Replaced with Bosch 67756 (5161335AE)

Water leaking from exhaust connection above skid plate
I guess this connection came loose after I removed the exhaust to drop my oil pan. Need to quit being lazy and tighten it. I cant imagine that this would be my issue though.

If you're still here, thanks and sorry for the long write up. Didn't want to just post "stuffs all messed up. Figure it out" with no information.
What plugs does the tag under the hood say to run,mine ran like crap with iridium plugs!
 
When our '03 4.0 wouldn't idle, it was due to a failed/failing O2 sensor.
A new sensor resolved the issue immediately.