I recently blew a transmission solenoid with only 3074 miles on my 08 JK 4dr. I had no forward gears, but I did have reverse. When I got it back from the dealership it has this rough idle. It runs and drives fine but now there is a distinct roughness in the idle that was not present before the transmission issue. Dealer tried to convince me it was normal. I am thinking, Not so much!

 

Get this. Somebody......dealership? Quick-Lube? left a socket sitting somewhere under my JK. It got lodged in the motor mount causing metal to metal contact and transfer of vibration...........Works fine now!

 

And, you have a free socket! Those are what...$5 each? Nice!