I have a 99 F-150 XLT Supercab with Triton 5.4L and 170K miles. I have started hearing this wop-wop sound in the front end that increases as the speed increases. No sound while sitting idle or revving engine while at rest. Front drive side tire was bald on the inside of the tire so replaced all four as tread was wearing thin. Sound persists and is a little more noticeable when I go around a curve. What i know about trucks and cars can fit in shot glass so i won't embarass myself with a guess. Also possibly unrelated the truck shutters when i hit the brakes from high speeds.

 

Sounds like you need an alignment and get the rotors turned.

 

The truck rolls pretty smoothly while I'm cruising no shake at all just the sound womp womp. If you take away the shuttering of braking is it still an alignment issue?

 

The front tire being bald on the inside indicates an alignment issue. The shutter when braking is a warped brake rotor. Turning or replacing will fix it.

 

check the ball joints too.