2001 Blazer front end? noise

I have the weirdest noise in my 2001 2wd, 2dr Blazer. About 10 feet after moving forward/backward, there is a loud "bang" that sounds like it is coming from the driver front side. I had it to the dealer several times, and they cannot find the problem. It will only do it once once the car is on. It will do it again if you turn it off then restart it. The dealer has removed/checked the front suspension to no avail. Anyone have any thoughts? Thanks.

How about this for a guess: The left front disc brake caliper is sticking and releases after the rotor rotates and frees the caliper. Try coming to a stop using only the parking brake, shut it off and restart and see if the noise is still there.

It sounds king of like the spring is moving. That kind of a spring/bang noise. When I leave for work in the morning, after going about 10 ft from where I started from, I will hear the noise. I could drive all day and it will not come back. If I turn the car off for even just a second, it will do it again in another 10 ft or so once I restart it. It will never not do it, whether the temperature is hot or cold (I live in Cleveland, OH). I would think that if a caliper was sticking, the noise wouldnt only happen if I turn the car off then take off again????
Note: the dealer found a TSB regarding a sharp edge of the spring cutting the spring pad. They pulled the spring out and inspected it, and put a new spring seat in it. They saw no visible problem. The noise did not change at all after that happened.

Whatever it is, my 98 does the same thing. It's just every now and then, but when first moving (say 2-5 feet), it sounds like something flops and hits the bottom of the floorboard underneath - like one hit with a hammer. Mine's on the passenger side front, however. It has been doing it ever since I got it in 2001.