I'm infuriated and at a loss, hoping someone here can help me after 4 months and over $1000 spent. Starting back in Sept, had a very rough idle on startup. Truck is shaking and not getting consistent power. Needed a new water pump anyway, so had it towed into my local mechanic. Replaced water pump and fuel sensor to address the idle issue, as it was corroded and seemed to be the problem. Drove fine home from the mechanic.

Few days later, same rough idle on startup. Towed back to same mechanic. Left it with them for 3 weeks and they spent several hours over many days troubleshooting. Said it would run fine some days, then experience the issue others. They ruled out several issues, but couldn't identify the root cause. Said it looked like possibly a PCM issue and would need to go to the dealer. Ran fine on the way home again.

Once home, I hit the forums looking for answers and found instructions on resetting the PCM (via removing PCM fuse and turning ignition to on position, etc). Did that and continued running fine...for about a month and a half, thought I'd found the issue.

Then a couple of weeks ago hit the same issue again. Had it towed to dealership...against my better judgment. They found a PCM software upgrade that was needed, which they did, and narrowed the issue to the spark plugs (?!?!?!), which needed changing. Really didn't feel like that was the issue, but went ahead with it. They kept it a couple of extra days to make sure it was running right, which it was. Charged me $700 for that...Drove fine home and 2 more days, then this morning, same rough idle on start. About blew my own gasket at that point.

I need help figuring out what this is...mechanic and dealership couldn't find it, but hoping you geniuses have some better (and hopefully cheaper!) ideas. It's 2007 1500 Thunder Road package w/5.7 Hemi. About 112,000 miles. Once I try it a few times with the issue, I get the flashing check engine light. It doesn't return any codes for me via ignition, but the dealership said it showed multiple cylinder misfire codes. I've had very intermittent cylinder misfire codes in the past, but always sporadic and corrected themselves. I've been working from home since March, so not driving everyday...usually only Thurs - Sun, so will sit a few days in between.

Anybody else had similar issues? Any help at all? Thank you!

 

What type of spark plugs were used to replace the old ones (Platinum, Copper, etc.)? Also have you thought about checking if the fuel filter is clogged? Maybe try running a bottle of 'Chevron Techron Concentrate Plus Fuel System Cleaner' through the gas tank.

 

I'm having pretty much the same symptoms with my Dakota, after all things listed here I've now got the check engine light showing a bad catalytic converter. Did you ever get a resolution?

 

What impact does the type of spark plug have on the idle? Is one better than the other? I put new platinum plugs in mine while experiencing pretty much the same thing that this fella is and it's running rough right now (my original post here). Also, would running the techron cleaner be advisable if there may still be remnants of seafoam in the tank? I added a full bottle to 1/2 tank, then it sat for weeks and I topped off the tank and it sat for weeks again, now driving it it's super chuggy and I have almost a full tank and I don't know if I should just try to run this gas out or go straight to replacing the catalytic convertor because the almighty check engine light says I need to. Sorry for hijacking the post, but, I mean... I need answers! Thanks!!

 

These trucks are picky for copper plugs only. I would run through the tank and then add the Chevron Techron after the fact. Ideally though, you want to run your truck on copper plugs.

 

Bad fuel injector(s)?