Help, My 2000 astro stalls sometimes

I have a problem. I turn my van on and sometimes it stalls sometimes when I turn it on and put it into gear. Yesterday I was pulling out of a parking stall and it stalled I tried 3 times to resatart and it finally did. I am stumped. I took it to an electric shop and they checked and found nothing. What could be happening? Please help.

I have a problem. I turn my van on and sometimes it stalls sometimes when I turn it on and put it into gear. Yesterday I was pulling out of a parking stall and it stalled I tried 3 times to resatart and it finally did. I am stumped. I took it to an electric shop and they checked and found nothing. What could be happening? Please help.

What engine and transmission and mileage?
Tune up history?
Any check engine lights?
Does it stall from low idle?
Is it losing spark or fuel pressure when it does it?
Have you checked for codes?
MT

I tuned it up around 125000 it currently has 170,000. I believe the wires were not changed. Also it is a 2000 with the 4.3 litre engine. I wouldn't be able to tell you what transmission it has. I have not checked for any codes.

No stalling at low idle and no check engine lights.

I am going to give it a tune up on weds.

No stalling at low idle and no check engine lights.

When it stalls you need to check for lose of spark or fuel pressure or both.
You will need a fuel pressure gauge on it to check fuel pressure.
Hook up a fuel pressure gauge to mirrow or tape to windshield.
And read fuel pressure when it stalls.
Also listen for fuel pump running.
Here is some guide lines on fuel pressure testing.

Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

Also a good scanner may show a problem like stored code or bad sensor reading.
Have you looked at that fuel filter or checked spark to plugs for good hot blue fire?

Another I noticed on my car was that When I would put it into gear some of the dash lights would go on and there would be a voltage drop.but all the lights would go off immediately and voltage back to normal at all times. The thing is that it is only when it wants to do it.