follow top hose from radiator to engine,thermostat usually in the housing at the hose,to test remove the housing for access and dip thermostat in pan of boiling water,should see it opening after a short while,any doubt,replace,top up coolant/a/freeze mixture,chokes are normally controlled through sensors/ecu`s nowadays and may need to go to someone with correct diagnostics to repair
cdc, November 2010
