Rough Idle and Knocking engine noise
alot of the time it's carbon buildup on cyliners. alot of dealer mechanics don't check the TSBs, so you better check yourself.
i had similar problem on 3.8L , dealer wanted to tear down
engine and charge me. they didnt check TSB and i found it myself.
ended up cleaning off carbon and getting out of it spending
$50 bucks- not bad.
Tango.