I have a 1994 voyager 3.3 litre it back fires when in drive under load through the throtle body and runs rough in park it does not back fire in park and it started to idle high at 2000 rpm in park and in drive now and throttle body sounds very loud now when sucking air in what could the problem be
Check for a vacuum leak for starters. Excessive air will give a high idle. Just follow your ears. When you get to where a sucking air sound is, spray a little carb cleaner in that area and listen for an idle change.