Soooo I have a 2011 ram 2500 5.7 hemi. Been struggling on random/multiple mysterious misfires. This last monday the shop hadn't figured it out because it wasnt misfiring. I took it out and drove it hard for about 15 min. and the misfires started back up. They plugged the truck in before I shut it off and it read that cylinder 6-7-8 were dead, 4-5 were misfiring and 2-3 were fine. It sat for 2 days and it is Wednesday and I picked it up and it ran fine amd drove fine for the 15 min. ride home. So what would cause such a rough and ****ty running motor and then after it sits a xouple days it goes away and runs fine?

 

Something gets hot, and fails. Can you do data logging?

 

Not sure what that intails

 

The common link here is the PCM. The computer commands the coil packs to fire as needed. If you got a loose connector at the PCM that could explain it. I would disconnect the connector and inspect the pins for corrosion.