well, i just got off the phone with the guy from the alignment shop (basically all they do there is suspensions), and he said that hes almost positive that its a wheel balance thing, since it does it all the time at the same speed. the place that i bought my wheels from mounted and balanced my wheels and tires for me, but they used the stick on weights, the guy at the alignment shop said hes gonna get rid of them and put on some clamp on weights (those stick ons suck.) just for piece of mind, i asked him if he could just take a look at everything else and if something looks suspicious, check it out, and he said that he would, at no charge, unless he finds something (he shouldnt find anything though, since it was just inspected last week, but just in case.)
and mrboyle, yeah, ford says they re-aligned it, but maybe they didnt, or maybe they didnt do it right; because of my wheel and tire setup, the alignment machine needs a different little adapter thingy to do it right. i dont trust ford anyway (service writers or technicians.)
thanks everyone for the input.