28chevyguy, you inspired me!! After reading this thread and your predicament, it sounded very similar to the problem I have with my son's Camaro. One day it was running ok, then it just started running like crap. Backfiring through the carb, 0 vacuum, Wouldn't stay running. After a lot of work, trial and error and asking for advice, I narrowed it down to the coil or the distributor.
I have had a new coil for the car sitting on my workbench for over a month, I put off installing it because, in my mind, I knew it wouldn't make a difference. Anyway, today I went out and put the new coil in the car........It started right up!!! I took it for a spin, it ran great for a 6 cyl.
Thanks 28chevyguy for giving me the push I needed, that you didn't know you gave