Fairly new member here, never post much but do alot if reading. This site is a great resource.

My '99 F350 DRW has 73,200 orig miles. Gassed up Saturday night drove it a few miles, parked it. Got in it a couple hours later started it up and was letting it sit and idle a minute before pulling out. Seemed to be "loping" just a tiny bit, I could here the exhaust kinda pulsing, but didn't notice the tach doing anything unusual.

Drove it an hour home, seemed to be a bit worse when I let off of it to back in the driveway. Next morning when I started it and let it warm up before I pulled out it was even worse. Truck ran just fine out on the road, no hesitation or stumbling. Put some gas treatment in it yesterday thinkin I may have gotten some bad gas Saturday night, hasn't made any difference. I've noticed if I hold the throttle open to 1500 or so it will drop down to 1000 or so and pick back up. Foot off the throttle its down below 1000, doesn't die, but sure acts like it wants to.

I recall having to clean and eventually change the Idle Air sensor on my old '97 7.5L a time of two, its acting very similiar. The PO of this truck put new plugs and boots on it at 63000 miles.

I'd be open to your thoughts and suggestions please...

 

Check for vacuum leaks first, that PCV elbow at the throttle body is a known problem.

 

Apparently when I gassed up on the way to the farm Saturday I got about 25 gallons of crappy gas. I dosed it with four bottles of fuel injector/gas treatment. On the way home from work last night I pulled up at a red light and it just cleared right up. Runs like a top now...