I'm not even going to try and get into front end guesses. Before you and your tech go "throwing parts" at it might I suggest the tires. Also, were the wheels ever crunched in the past. (curb damage, etc) Just a small bend, nick, or anything to get it out of "true" can rear its ugly head at 80mph. If you know a good wheel repair shop locally great, if not you can try Rennsport. (link at bottom of page) I have driven some tires (conti's) that just didn't want to balance completely. They seem fine at most speeds but certain speeds seem to bring out the shimmy in them. Also those tape on wheel weights seem to be tougher to get a perfect balance but I'm assuming your using OEM wheels with the standard type weight.
When you say it pulls, does it pull while coasting? Does the amount of pull change when you hit the brakes? (with hands off the wheel) Since you just changed pads take it easy on the brakes for a short while if at all possible. Also keep an eye on the rotors. If there is some minor warpage in them it will manifest as a ring of corrosion where the pad is not making complete contact. Start with something you know can be improved upon, the tires. We can take it from there.