I just change new radiator and radiator cap on 2000 nissan quest .go on freeway .and know temp gauge very high i stop the car wait and run again ,now see a gauge go high and drop down to normal ,what is the problem ? can i goin to change new thermostat?

SOURCE: 2000 Nissan Altima temperature gauge and heater problem

sounds like you need to replace the thermostat.

SOURCE: 1996 Pontiac Grand Am overheating

If its the 3.1L it could be your intake manifold gasket , the material used for the gasket does not react well with GM's Dex-Cool antifreeze. The leak may not be apparent at first, but I would pressure test the cooling system. If you look at the front of the motor by the belts , try to peek down at the intake manifold and check for slight seapage to an obvious leak.

If its either of the Quad-4's they were notorious for heads warping or cracking.

SOURCE: 2002 KIA Sedona Overheating

most likely, replace thermostat .

SOURCE: 2001 dodge stratus engine temperature gauge spikes occasionally

Look for a loose connection to the temperature sender unit on the motor.
If all connections OK, you may need a new temp sender unit.

SOURCE: 1999 Oldsmobile Bravada Heating Problem

when engine is cold remove radiator cap and check coolant level,sounds like it is really low and has an air pocket in it.