[tableman]

When doing a tune up on the Astros, you have to make sure all you spark wires are nested properly or you will get misfiring happening between the spark wires and the aluminium heat shield on the inside of the dog house.

Especially the spark wire from the distributor to the coil, there is actually a GM service bulletin that states that wire must run under and around the objects in the path rather then up and over, which is what most of us would do when running a new wire.

To verify if this is you problem, take the dog house completely and look closely at the inside aluminium heat shield, if this is your problem you will see little arc holes in the shield, that resemble and spot welding mark.

This happened to me after doing a tune up on my 1996 Astro. 2 weeks after the tune up it started misfiring, it took me a month to solve the problem. I only saw what was happening after in frustration took the dog house completely off to get more access to the engine, and as I set it down my eyes caught the arc marks.