I forgot to ask, Is the temp guage reading normal or not? It could be any of the things mentioned in my previous reply. As for muffler ques, I have an incinerator, identical to flomaster, but has a deeper more mellow sound. People ask if I have a V8 because that's what it sounds like and I do not have a low end power drop. You need to have at least 32" of tailpipe for it to work properly. I also have a 3" barrell tip on the end.

 

From what I remember I had the same problem with my 1993. I believe I fixed it by flushing out the cooling system. I also remember that I had to replace the radiator some time back because the fins that zig zagged between the cores were all deteriorated. Good luck. Mine still runs great with over 180,000 miles.