I have a 1993 chevy s-10 blazer 2wd with a 4.3. vortec and it sometimes idles rough and when it does black smoke comes out of th exhaust i have changed the plugs wires rotor button and distirbutor cap and by the waay it runs great out on the highway and around town just when sitting idle its kinda rough
Cars & Trucks - Chevrolet - Blazer - 1993 Chevrolet S-10 Blazer
Answers & Comments
Two things pop to mind with this truck, first these motors are notorious for having bad intake gaskets take a flashlight and look very carefully around the valley of your intake/block-head seal you'll possibly see either antifreeze leaking or a weird looking whitish or greenish sort of foam you can also use propane around the seal and look for obvious idle changes, I have done tons of these intakes in my shop, the other two things I would suspect if that looks fine are 02 sensors, or maf sensor.
Check gap on plugs or choke not operating properly,or fuel filter