Of course there is more to it then just this (wax remover, cheese cloth, certain techniques) but...

My advise would be to WET sand it all off with 1000 grit paper. If the process is too slow, try 800 grit and so on. Once all the primer is removed, sand the existing clear to the stock base coat while making sure you do not go too deep (to the original primer). Once the car is sanded to the same consistency (no primer or clear left), you'll be left with the original base exposed. Use a cheap clear coat and give the car a few coats of clear. I've always used the compressor / spray gun combo but try a spray can from crappy. My suggestion is to try this technique on an old fender or something before you try the actual car.

You'll likely be amazed at how nice it'll turn out.