Auto body repair & detailing: Rust flakes in clear coat?, ford excursion, rust spots

Question
I have a 2002 White Ford Excursion.  Last fall I noticed rust spots/flakes on the finish. I worked very hard and removed them all with a rubbing compound and paint cleaner.  They are back again. It is not in a few places but all over the vehicle.  They are mostly on the lower half of the vehicle-beneath the door handle. The rust spots even appear on the back which is fiberglass and on the plastic of the running boards. They do not appear deeper than the clear coat.  What could be causing this and what can I do to prevent it.  Could something have been picked up off the roads?  Thanks

Answer
Darcy about the only thing you can do is to put and keep a lot of wax on the excursion.it sounds like you are getting the specs from some sort of grinder wheel, a lot of times when some of the grinder specs land on anything they sit there and start rusting.