I have an old 1980 450sl that I resurrected from 5-10 years of sitting. The car only has 37k miles. Gas tank is clean and the car is running good. New plugs, distributer and wires also. The car was running super super rich and missing until I leaned up the mixture via the air/fuel adjustment screw. I want to check some of the intake/air components that could possibly be varnished stuck or clogged. I just want to make sure that I didn't mask a problem by adjusting the mixture. The car still has a very very slight lul/miss in the idle but it is 99.9% better than it was before i adjusted the mixture.