how do I lower the idle on a 86 astro van
How high is the idle?
Does your engine have fuel injection or a carb?
It's likely a throttle body, 4.3L, the throttle body gaskets can degrade and leak air into system causing high idle. I'd look for any vacuum leaks, a short blast of starter fluid near a suspect joint or crack can cause a tell-tale jump in idle. Fuel meter is another place to look if it's dumping excess fuel.
Looking for a Used Astro in your area?
CarGurus has 149 nationwide Astro listings starting at $1,600.
Search Chevrolet Astro Questions
Chevrolet Astro Experts