Engine Stumbles at Idle F450 1989

[ironworker]

I have a 1989 F450 460 engine that stumbles/hesitates at low rpm or idle, then runs fine after that. Put in new spark plugs, fuel filter and air filter, but still happens. Any suggestions? Thanks, Mike

 

[50F1Wrench]

I have a 1989 F450 460 engine that stumbles/hesitates at low rpm or idle, then runs fine after that. Put in new spark plugs, fuel filter and air filter, but still happens. Any suggestions? Thanks, Mike

<_< :-" :mellow: Hey, Here's my experience with these engines. First, check for a vacuum leak at intake. I use a propane bottle with nozzle to test. Have used carb clean but it's possible to get flash if ignition is faulty. Also, second possibility could be a faulty TPS. These sensors can fault anywhere in the resistance coil. If you sit and idle for long periods, it can wear at that point. Hope this helps. 50F1wrench.