1996 Astro 4.3L won't start?

When I turn over my van, there's a 50% chance it will start... So far I have replaced the fuel filter, the coil, and distributor cap. The pump is working fine because there's fuel pressure, and the plugs and wires aren't very old- and it's getting plenty of spark. And I know it's not compression because when it does run, it acts like there is nothing wrong, and the worst part is it's not giving me any diagnostic troubleshooting codes... Does anyone have any ideas or similar experience with this engine? Any advice is appreciated, thanks.