[bskouby]

The truck has right around 39,000 miles on it. No cold air intake, just the gotts mod. I do have true duals, magnaflow X pipe, no mufflers. Stock tire size, no other modifications.

No customizations at all when running the 93 canned performance tune. And yes, I *am* running 93 octane (dang stuff was almost impossible to find around here) with the 93 performance tune. I ran the 87 canned tow tune for a couple of months without any issues at all.

I am into my third day with Bills 87 performance tune, and am happy so far. I think it has more power than the 93 performance canned tune, and best of all no other vibration/bucking issues.

What concerned me was how violent the vibration/bucking was when this happened. It almost felt like the U joints had frozen up on the drive shaft...but they are fine as well. At first I could only get it to do this on hills when running in 4th/TQ lock and easing into the gas. Then it started showing up on flat highway runs. After the highway nonsense started, I switch back to stock and I could not get the issue to reappear. I then switched to 87 tow canned a few days later and still couldn't get the issue to repeat. By then my tunes showed up from Bill and I loaded them up.

I guess I will chalk this up to something strange with the canned tunes. I thought I would throw this out there and see if anyone else had ever had these particular symptoms.

This truck does shudder from time to time, but every Ford truck I ever owned did stuff like that. I do think I need to get the tires balanced as I do have some minor vibrations at highway speeds, but this was a much more than minor shudders and tire vibration. Heck...I thought all four wheels had fallen off of it the first time it happened!