KZZman

I was excited to purchase my first Z after years of admiring them. I just purchased a 77 280Z with only 10,000 miles on it. I did a full blown tune-up plugs, wires, cap, roter, fuel filter, before I started putting miles on it. I brought it home today, and it started to run rough after it was warmed up. It started backfiring and was running at 500 rpm at idle. I looked around on past posts and noticed quite a few owners have had the same problem. I see quite a few suggestions, but I don't want to start throwing a bunch of parts at it if I can help it. Could anybody give me some solid advice. I see possible solutions as replacing o2 sensors, coolant temp sensors or start messing around with the AFM.