I had run some injector cleaner on my 92 Astro and it ate away at the injector O rings which caused flooding problems. I discoverd this by turning the key in the run position (this engages the fuel pump) while looking at the throttle body and noticed gas dripping out of the fuel injector (mine is a throttle body design). I replaced the O rings and has been fine since then. Lesson learned - don't put in any additives unless it is a last resort.
Did it ever occur to you that we Chevy owners spend all of our spare time fixing our Chevy's and don't have time to spend on the internet. Kidding aside my experience with cars (mainly GM and Honda) is that if you spend a little time doing preventive maintenance you will spend a lot of time with trouble free driving.
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles