Have an odd vibration problem that's getting worse by the day. Started about 3 months ago. On the road, my 02 will start vibrating at exactly 66MPH. It gets at its worse at 70MPH, so bad things in the cab start rattling. It stops at 74MPH and doesn't reappear all the way up to 90 (fastest I take her on the highway).
The vibration doesn't seem to be from the front end, the wheel doesn't shimmy along with the rest of the truck.
The tires are new, the wheels have been balanced and checked, the alignment is fine far as I can tell. The issue started before the new tires, so it's not them.
Odd part: When it's vibrating, if I step on the gas, the vibration either quiets a lot or stops altogether. I let off the gas, it comes right back.
Seeing how I drive 140 miles on I-75 every weekend, and the speed limit is 70, this is driving me nuts.