Overheating...., Diagnose my problem? Options

[95GTCelica]

Alright 6GC People I need your help...

Today after driving for about fifteen/twenty minutes I parked and noticed that the temp gauge read above the red line and the H. Popped the hood and heard gurgeling coming from the radiator with some overflow. I let it cool down for an hour then came back and drove around the block a couple times. I noticed that the temperature goes through the roof when it starts and slowly climbs. But when i hit about 40mph it cools down to about 3/4 of the way and when i stop it goes straight back up. I had a similar problem like this before and it was a bad water pump which was replaced a few weeks ago. Today there was no coolant on the ground just the few drops that spilled from the overflow. The engine seemed to be running fine and I wouldnt have noticed anything wrong with it unless i looked at the temp gauge. So can anyone help me? Any ideas? I'm stumped.

[95GTCelica]

does your coolant smell...well it should smell like coolant. if it smells sickly or like exhaust...not a good thing.

Yes it smells like it should...

I picked up the thermostat today, twenty bucks from the dealer so i figure if i ordered it off the net it would come to about the same. Tommorrow morning I will switch it out. I will also check on the debris in the radiator fins while im there, but i dont know what could be in there.

By the way thanks to everyone. This is really helpin me out.