The 1999 Chevy Astro van, regardless of whether it has the 4.3L V6 or the 2.0L I4 engine, will have its firing order listed in your owner's manual. There is no single firing order for all Astro vans of that year. The firing order depends entirely on the engine.
You'll need to check your owner's manual or a reliable online repair manual specific to your engine type (4.3L V6 or 2.0L I4) to find the correct firing order.
