i have a 2003 vw jetta1.8t at idle the vehicle temp is at 190. wheather im in park or in drive, the vehicle begins to over heat. the vehicle then cools back down to normal operating temp. any ideas what it could be?? auxillery pump was replaced.

 

If the engine over heats and cools down randomly it sounds like a sticky thermostat possibly. They are pretty cheap and usually easy to change out.