Turn Signal Bulb issues

I would guess you have something loose that is allowing the bulb to --what's the word?-- shimmy and shake as you go down the road. vibrate. Shakin' itself to death.

You have all the braces on the bumper? Anything you can "move"?

I don't see any possible way this can be an electrical problem, unless --have you checked that the parking lamps are actually on the smaller filament and the signals actually on the brighter filament?