1998 Chevy Camaro 1998 Camaro Random Misfires V6

My engine has been randomly misfiring for almost a year now. I have taken it to the dealerships and other local repair shops and everytime they fix something, it works for a few months, then the problem comes back. So far they have replaced:

Wires
spark plugs
cat converter
O2 sensor
#6 fuel injector
coil packs

There was a similar problem posted on a forum, but it was for a firebird. The solution was a bad wiring harness and I am wondering if that could be mine as well? recently the problem came back, and now that I have gone back to school, I dont have the money to send it to a dealer or repair shop. Thanks for the help.
Also, here is the link to the Firebird with a similar problem:

http://www.2carpros.com/forum/1998-firebird-random-misfiring-at-different-times-vt45093.html