Bumpy Braking --needs help--

I've got a 99 silverado 5.3 L z71 w/ 65000 on it. I just got done taking off the front rotors and i had them turned. Put the rotors back on and drove around and everything seemed hunky-dory. About two days after the repair i'm braking again and it starts to get a lil bumpy again in the front. In a matter of seconds the bumpy-ness gets 10 times worse than it was before (in the front wheel). It's almost a knocking sound but it can be felt in the brake pedal. I took the tire off and checked the calipers again, they're on tight. I'm not sure what else it could be. Got any ideas? Thanks for your help.

My guess would be that the rotors are shot. If you verify this and plan to keep the truck for another 65,000, I would recommend paying a little more and purchasing some quality rotors that meet or exceed OEM specifications. I have found that the less expensive rotors don't last long.

I just got done taking the rotors off of the front. They look exactly the way they did 4 days ago when i replaced them. Maybe i'll switch the front two rotors and see if the braking weirdness switches sides. Then i'll know i've got at least one bum rotor. This truck is starting to frustrate me.

I switched the passenger and drivers side rotors. The thud sounds when braking still occur on the drivers side. I think i've illiminated the front rotors as the cluprit. Anyone have any ideas what i could be?

Are the tires ok? Made any mods recently to the suspension? If four wheel drive, what is the condition of the CV joints? Any loose plastic skirts in the wheel well that might be contactinng the tire?

possibly somethings wrong with the abs braking system.