My truck has developed a vibration while on a road trip to the Washington, DC area. It started while driving through WV on I-64, which is pretty bumpy around Beckley. The vibration shows up above 50mph (when the torque converter locks up) and appears to go away above 75mph. It also goes away when I let off the accelerator pedal. I am roughly 600 miles from home and would like to make it home on Wednesday. Any thoughts on what the issue may be?