Hi again - today I decided to replace my plugs, wires, cap, and rotor...so I tried my hand at something I haven't done in years - tuning a carb =) It's a crate GM 350, edelbrock 1406, in a 70 blazer (and I'm just outside LA, at about 1000 ft elevation). The best manifold vacuum I could get was almost 19" Hg, at around 600rpm. I backed the mixture screws out a bit, and ended up at 1 1/4 turns out - does that sound borderline too lean? I just don't want to damage my pistons and such. Another thing is - my idle is somewhat unstable...it drops about 50-100rpm every so often, but my manifold vacuum stays rock steady. And I mean zero movement in vacuum whatsoever. Any clue what could be cause this?