Hey everyone, got a question. I have an '89 H.O. switched over to a carb. I used to have a Holley 670 Street Avenger on it, but i could never jet it lean enough, it was always rich. The car always ran great even with it running rich all the time, so i left it on there. For about the last 8 months the damn thing diesels every time you shut it off when it's warmed up. I have just recently put a Holley 600 on it and the plugs are now light brown. I have ran cleaner through the gas and down the carb, but it still diesels, how can i correct this? The timing and idle are all set correct. anyone got any ideas?