It sounds like your coats are going on a bit "dry". Ideally, you'll lay the stuff on just short of running or sagging, but that's obviously not a fun place to be when it actually does run.
I used Rustoleum's comparable chemistry paint on my son's electric guitar body this past weekend, and I found it very difficult not to "orange peel" the finish. It was hot and sunny on Saturday, so when we top-coated it with clear on Sunday we did it in the morning and in the shade of the house. The finish came out great, even smoothing out much of the orange peel of the color coat underneath.
-Tim.
-------------------- "We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"