"07" Bucks with cruise on @ 76 mph down hill

[capehoorn]

"07" F250, 4x4, 48000 miles. Occasional buck or feels like abs is applying rear brakes real quick for only a second. Only does it with the cruise on @ around 76 to 78 mph on a long down hill stretch. One time the abs light came on but only one time and it went off when I stopped at the next rest stop and turned the truck off. It didn't come back on but the same bucking happened again twice over the next 200 miles. Any idea what's going on?

[Firematt71]

do you have an idle control on your truck?? If so, does the truck have a "stumble" when you idle the truck at high rpms?? Also, is the truck still under warranty??

[capehoorn]

I did the high idle mod using one of the upfitter switches. I don't use it that often but when I do I don't seem to notice a stumble, but then again when I do use it, it is in the cold winter months and I set it and go back inside the house. How long would this "stumble" last and would it be obvious? The truck is out of warranty except for the 100,000 mile engine warranty.

[Firematt71]

well the stumble ive experienced happens around 2300-2600 rpms...and if you are truckin down the road at 76 mph i would assume you would be running in that rpm range depending on your gear setup. i have the same issues..downhill / high speed bucking at higher rpms. this seems to be a engine issue..not a abs braking issue. i would check your fuel filters first..then i would take it to your dealer (as you are still covered for engine work) and ask them to take it for a drive test..it may be fuel system related or a bad sensor...