Steve, Sorry to hear you having problems. Going 2 tight is just as bad as going 2 loose. Sometimes I have the same problem after having my hub apart. It might take several adjustments after putting it back togehter before you get it just right.
There are many replacements hub's, it all depends on how much you are willing to spend.
Here are a couple of links, one is how to rebuild your coaster hub and put it back together. Some pic's to make it a little easier. The other is the bicycle tutor video, it's not a coaster brake but it might help you out.
http://www.parktool.com/repair/readhowto.asp?id=104http://bicycletutor.com/overhaul-wheel-bearings/