Clunk in front end, help

[rice_eater]

I'm getting a clunking sound coming from the front of the car (at least i'm pretty sure its the front, kinda hard to pinpoint noises exactly while driving). Its not a real heavy clunk but its not light either. its definetly metalic sounding, steel though not the high pitch tink of aluminum. I had my tie rods, ball joints and steering checked and I was told they were fine. this clunk comes and goes. it will be there one week and gone the next, only to resurface the week after. If i had to guess i would say its coming from the strut area. both sides now make the noise, it was just the passenger side to start with. The shop i took it to guessed either bad strut mounts or stut malfunction. the car doesnt bounce over bumps so i'm pretty sure the struts are ok. Could it be strut mounts? how do i fix something like that? BTW, this clunk does not occur on all bumps, only large potholes in which the wheel suddenly drops a good bit and then is quickly forced back up as it hits the other side of the pot hole, or sudden loads while turning, such as hitting a bump taking a corner fast. (i dont think its the cv joints, i drove in a tight circle and didnt hear any clicks or grinding) I can sometimes get it to make the sound if i jack up the front (taking weight off the suspension) and setting it back down rather quickly and then jumping into the seat quickly or onto the fender, to simulate a sudden load. anyone know what could be causing this and if its a serious problem or not?