'04 Durango ST with tapping sound

I have a 2004 Durango ST, approx. 50K miles on it, w/ 4.7 L engine (no hemi). There's been a tapping noise (sounds like rocks being thrown at the floor board) that you can also feel underneath drivers side floor boards. Brought it to dealership, they replaced a bad tie rod and fixed a loose piece of the body & we purchased new tires.

After we brought it home, the noise continued and got worse. Took it back to the dealership, they proceeded to tell me that the whole front end looked fine. Well, I don't know much about cars, but I know that sound isn't normal. Also, on the way to the dealership, the ABS light came one. It's being replaced and the tech told us that the ABS is what was causing the tapping. Also that the ABS will tap and the brake pedal will pump when engaged. Well, I know this, we lived in Alaska for 5 years and had many occasion for it to engage. It's not the same noise or feeling!

Other details. It only occurs at lower speeds (either that or the engine noise covers the sound at higher speeds.), It happens after driving for awhile or if it's hot out, it happens no matter whether you're braking, coasting or accelerating.

I need to know what else it could be, or if the ABS could really have been causing it all this time. (Been happening for about 6 months). I don't want my car to leave the dealership without this being fixed!