Mechanic went to change out the thermostat on the 03 Cruiser...drove it back to me..overheated when he got it back...removed the thermostat to see if that would at suppress the overheat problem until the next day...overheated again...not more than 20 minutes later

Removal of the thermostat from the cooling system is not a good idea. This upsets the coolant flow rate in the system, and that can cause the engine to overheat, even when no other problem with the cooling system exists.

Try to identify the cause of the overheating.

Ensure that engine tune, or other engine mechanical fault condition is not the cause of the overheating, then go through the checklist following:-

1) Check engine cooling fan/s are operating as required when engine temp rises above cut-in threshold - check fan control relay is ok,
2) Check for collapsing radiator hose on suction side of water-pump when motor revs raised above idle.
3) Check coolant reservoir pressure cap is serviceable,
4) Check coolant system is properly filled - carry out any bleed off procedure specified to clear any air locks- (ensure heater core coolant flow is turned on).
5) Check for combustion gas bubbles in the coolant reservoir while the motor is running - this indicates a blown head gasket. If in doubt, take it to a radiator shop and ask for a combustion gas check on your radiator.
6) Check condition of radiator core:-
i) for blockage of air flow to (bugs/grass etc),
ii) for core internal blockage to coolant flow,

If all above ok, replace the thermostat again (also ensure it is not installed upside down) - faulty new thermostats are not unheard of.