Latley my 5.9 has been idleing right above 500. sometimes it even dips to 500. At times ill be waiting in a intersection, and ill have to kill my music because I think my truck has shut off its so quite. Plus it hardly sounds like I have my Magnaflow now. Anything I can do to help this? Like maybe a new higer output coil? Any ides would help im afraid itl get worse. I did a full tune up and cleaned the IAC not too long ago.