I have a 2003 F350 Dually with 6.0 Powerstroke. I tow 35’ gooseneck two place car hauler. I’m having intermittent issues with it suddenly dropping power as if throttle was lifted. If I’m in cruise control, it will drop out of cruise. The glow plug heater light will flash briefly but no other dash lights. No check engine light and no codes set. If I lift and repress throttle it will pick back up. At times it will do this once and be fine for days. At times it will do it twice in a day. Then it will take spells were it will do it repeatedly 3 to 5 times in a row. If it does it starting from a dead stop it may or may not stall.
I suspect the Pedal Position Sensor but I suppose any electrical interruption could give same symptoms and require throttle position to be reset. I’ve tried to make it happen so I could demonstrate to a mechanic but can’t. I’m reluctant to take it any were because as with all intermittent problems, if you can’t see it happen it’s hard to diagnose.
Any Ideas what could be happening here?
Also Can the Pedal Position Sensor be purchased separate for this model or do I have to buy complete pedal assembly for big bucks ? P.S. This is the adjustable pedal position set up. P.P.S. New to forum please be patient I’m a poor speller and terrible with acronyms.

 

Do a search for harness chaffing. Sounds like that may be your issue. There are several threads and some info in the Tech folder for the common spots.

 

Do you have an obdii monitor? I'd start with looking a vref

 

pull the EGR Valve and clean it up they get sooted up , turn counter clock wise and pull straight up , be careful not to bend up the tabs, while your in there cleaning do the IAT2 sensor too

 

Thanks for the feedback. Checked for codes with Actron Plus scanner from Advance Auto, no codes found. Returned to Advance Auto, Could only get a handful of live data points. I can do and see more with Torque Pro on my tablet than with Actron. EGR was replaced a little over a year ago but I know they can cause all kinds of issues so I’ll pull and clean as suggested. Also will check for chaffing. Thanks.

 

I believe the glow plug light coming on is an indication that the pcm is resetting like you switched the key off. So, I suspect an intermittent open circuit or ground that cuts main power to the pcm.

 

Thanks Bryan. That would make sense and relate to npccpartsman suggestion of checking for chaffing.

 

Checked for chaffing under hood and wiggled every plug I could reach. Didn’t find any evidence of chaffing but found plenty of opportunity for it. There’s a plate on the driver side fender that 5 plugs are mounted to that is only secured with a panel fastener. Fastener was broke allowing plate to float. Couldn’t find the right fastener so I took 2 large wire ties passed them threw a washer, the plate, the hole in fender and another washer, then took 2 other wire ties cut, cut the heads off and synched them on to the wire ties on underside of fender with a wire tie tool. I think it made a tighter sacrament then the panel fastener. I would have just used a small bolt but my arms are too short to reach both ends. Also the wire harness that passes over the engine under the windshield had several missing fasteners. Replaced these and re-secured several other harness attachments. Lastly I started truck and poked and wiggled everything I could safely reach to try to get it to act up. Don’t think I really fixed anything but as with all intermittent problems I’ll just have to drive it and see what happens and try and collect as much data as I can. I really hate to start blindly replacing parts If I can avoid it. Will post updates as I go. Yah or nah.

 

Did you clean the EGR Valve and the IAT2 sensor?