so my 97 ranger 4.0 with 202k used to idle at 600 when fully warmed up but now its around 800-900 and i can hear a whistle that i think is a vacuum leak when i goose the gas pedal and rev to around 1500 then drops down to 400-500 and the whistle gets a lot louder then it bumps back up to 800-900.. i have a little video of whats going on.. any ideas? i tried to locate that whistle but all i can tell is its louder under the truck than under the hood.. i just noticed that when i unplug the mass air flow sensor the misfire goes away and the idle drops down to normal.. is it the MAF or something else causing a bad reading maybe? i guess a VAC leak would be adding un metered air could be the issue?