I have a 2009 F-150 XLT 4x4 with 133K. Last night while driving in town (15 MPH) I was driving up a slight hill and all of a sudden I thought I had a flat rear right tire. Sounded like I was going over rumble strips. No flat. Started driving again, slowly and it happened again. Again, could see nothing wrong. Started driving and drove about a mile at 25-30 MPH with nothing wrong. Pulled out of parking lot turning right and it happened again. Once it starts shaking/shuddering I have to come to a complete stop for it to quit. Anybody else familiar with what might be wrong?

 

ever change spark plugs?..the rumble strips sound could also point to a bad torque converter

 

No, I've never changed the spark plugs. Didn't notice anything up until last night. It shakes very violently when this happens. It's more than just the sound I believe.

 

start with a plug change

 

I would also say start with a plug change, at 133k your in need. Check for bad plug wires since you will have them off and if you find one plug in bad shape and you still have the problem after the plug change I would look into changing that coil and wire on the cylinder with bad looking plug.
Sounds to me like maybe a coil is giving you problems at a certain rpm range.

 

Wheel Bearings.

 

Found the problem. It was the bearing on the drive shaft. It's a one piece drive shaft. Unfortunately I have to replace the entire drive shaft and can't replace just the bearing!