I have a chevy lumina z34 that stalls out. I drive the car for a little while it either drives fine but it stalls out alot. It stalls out when i get into parking lots or when I an driving main roads and it stalls out when I am at lights. Many things were done to this car already like the alternator. I am not sure what else to do can someone help me figure this out.

Can you be a little more specific? Does it stall out randomly, when you slow down, when cold, when warmed up, all of the above, none of the above?

it stalls out randomly, and when I sit at lights to long.

does the check engine light stay on and if so, have you checked the codes?

The check engine light does not come on.