You need an OBDII scanner to retrieve the trouble codes.
The transmission in a 2000 Astro is a 4L60E.
The Chevy Astro was a van produced in 1990-2005. The it is rated poor in fuel economy averaging around 15 miles per gallon. You can pick up a used one for under $2000.
morelikly nothing , just replace it with the right one
It is at the front of the engine kind of high under the p/s pump.
GREEN color.
5W30 oil.
dextron 3
4l60e
Dextron II fluid.
That kind of key was not used in 1995 models.
4.3, 5.0, or 5.7 liter V/8
87 octane should run just fine.