1997 Chevy Astro Astro start fine, run fine on idle, but no

You did not say if the service engine soon light was on but I have two suggestions.

#1 It is possible to have an exhaust restriction that will cause loss of power. Use a vacuum gage. Check vacuum at idle and then increase speed to around 2000 rpm and check guage again. If vacuum falls toward zero more than a couple of inches, suspect that you have an exhaust restriction.

#2 Due to the high mileage reported, it is possible for the timing chain to jump one or two teeth and the engine continue to run but have no power. You will have to pull timing chain cover to inspect and I would go ahead and replace timing chain and gears for routine maintenance.

Hope this helps
OTBlvr52

My 96 was stalling out as I accelerated it was the catalytc convertor changed it to a magna flow odbcII $80 at part source same at can tire.

Regards,

Chubber22