Overheating they say head gasket changed

If you have white smoke from the tailpipe, coolant in the engine oil, engine oil in the cooling system, that indicates a head gasket failure. However, the most definitive way to test is to have a hydrocarbon test done on the cooling system (checks for exhaust gasses that obviously don't belong in there).
If the system comes up clean, you still can have either a leaking intake gasket, partially obstructed radiator (many times flush will go around obstructions not through them), a malfunctioning electric fan or fan relay, or even an obstruction in front of the a/c condenser or between the condenser and radiator (leaves, plastic bags etc) Don't forget though even if the cause is other than a gasket, if repeatedly or severely overheated the head gaskets can also fail. That is why complete testing is very important.
good luck

My 2002 Venture is in the shop for the same reason, and it is getting all new intake gaskets and head gaskets and all new antifreeze and oil, and maybe new heads. about $1900.00, alot of money but we need the vehicle.

Not with all the efforts you have already done. It sounds like the head gasket is the last option. But try changing the radiator cap, I've seen them go bad and cause cars to run hot. I hope that would work, but if not, it's most likely going to be the head.