1997 Toyota Other temperature gauge/overheating

When im driving the temperature gauge will start to rise like its overheating ive turned the car off but there is no noises like bubbling from the radiator and there is no lost of water or oil I found out when it happens and I take my foot off the accelerator for a sec then push back down the needle drops back 2 normal ive removed thermostat and flushed out radiator but it still does the same I drove it around for about a month like that as my daily runner but then brought another runabout just for the time being if car I start it every 2nd to 3rd morning and leave it sitting there for 30 min most days longer idling and it doesn't overheat or anything can you please help it would be much appreciated