Just picked up a 94 with a 4.0 in it. Truck has 247,000 miles on it, and is in amazing shape. Anyway, it has a issue. When you start it, it revs to like 2500 rpm and slowly I mean slowly idles back down to around 1100 rpm. And then it will sit and idle at 1100 for a few seconds then it just dies..sometimes you can fire it back up and other times you have to go tap on the MAF meter before it will fire back up. Why would I have to hit the MAF meter? Also when you rev it up it revs up and it will stay at whatever rpm you reved it to for a few seconds before rpms come back down, but then the rpm comes down slowly..I just changed plugs with NGK platinum, and new ford wires...took off the IAC and sprayed it out with carb cleaner..cleaned up the MAF meter..and sprayed the throttle body with some carb cleaner..some gunk came out of there..not much though. Could I have a vacuum leak somewhere that would be causing this..Or do you think the Throttle position sensor coulg be bad? Or could the IAC be bad or the MAF??? Need help quick..

 

sounds similar to my bad MAF symptoms, except the RPM didn't drop any slower or faster. when i had IAC problems the idle would roam and sometimes sputter and want to die. i could swear i remember hearing these trucks don't like ngk plugs for some reason though...