I have a 2009 Sport 5.7 Hemi at around 20K miles it started witha rough idel, like it was missing. I have taken it dealers numerous times & they can feel the rough idle but when they hook it to the diagnostic machine it doesn't give them any "codes" so they say nothing is wrong. I drive the truck every day since I bought it brand new & something IS wrong & is getting worse & worse. I have changed spark plug air filters, oil changes & nothing seems to help even for a short time.

 

So sad that if the computer doesn't show a problem, then it's fine. Are there any real mechanics anymore? Just computer technicians with a wrench?

 

See if you can get an inexpensive compression check. My dealer charged about $125 for the check and discovered one bad cylinder on each bank. Did a double valve job under warranty and that corrected the rough idle.

 

Also some injector cleaner might help.