Bump! I have no idea what could be doing that, but I bet someone on here does. I know anytime I had violent shaking or weird things happening with the front end it usually had something to do with ball joints or worn out bushings. That's my .02. Good luck!

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2002 Ford Ranger with 142k
31in Cooper Discover ATR
Gibson 2.5in Cat back exhaust
CTC Camper shell
K&N Panel filter