my car has been idling very bad it jumps up to almost 2000 when i start it sits for about 7 seconds then drops but only drops to about 1100. so i took of my iac and cleaned it with carb cleaner put it back on and nothing. now not only does the idle suck but when i put the car in drive or reverse and the rpms drop anywhere close to 1000 there is a loud humming noise. the noise goes away after i rev it up but it keeps coming back. i dont know what it is maybe my harmonic balancer? any imput is appreciated thanks!