help!!!

99 astro just dies while driving, starts back up and does not do it all of the time! what could it be??

what are the trouble codes?

scan with an obd II scanner yet?

check engine light on?

loose battery connections?

vacuum leaks?

fuel filter?

spark plugs ok?

Start with your basics, fuel and spark. Make sure your electrical connections on your coil are tight and not corroded, check your distibutor cap and rotor, then check for proper fuel pressure. If you have not replaced your fuel filter in a while, it would be a good idea to do that now. If all of that is good, you might have the same issue I had on my 2002, the cat converter was clogged and when it would start to heat up the van would die. If all of the above checks out, pull one or both of your O2 sensors off and go for a ride. The van will be loud but I found it to be a great way to diagnose. If the van runs without stalling with the O2 sensors off then you know you have a clogged cat converter. If that is the case, you might want to shop around, they are not cheap. Removing your O2 sensors will get rid of the backpressure caused by the blocked cat converter.