Sudden heat...WTF???...Advice needed...

I was going to work this morning, all was fine, picked up my friend, we go on the boulevard and then Bam, the ding-dings went off, temp is redline...

Pulled over, stopped the car, waited 5 minutes, restart and redline again... I opened the hood, no leaks and the hoses were cold and the rad is full of coolant...

I had a custom muffler installed yerterday, I doubt it has anything to do with it, just thought I`d mention it...car was doing fine yesterday...

So I`m thinking thermostat, anybody has any other ideas....

Had the car towed home...I`m at work so I`ll check up on it this afternoon...

Any insight appreciated

Jeff

poss water pump.
they originaly have a plastic impellar and they break.
replace with new pump that has steel impellar.

I thought about the pump, I was hoping not.... After the car was dropped at my house, I started it one more time and for 5 minutes, it was stable in the normal range, like nothing happended??

Jeff

water pump/t-stat/fan clutch? those are the common ones.

Thermostat was changed 11/95, fan works...

I was told the newer t-stat were made to fail in the open position.... that`s why I`m worried it`s the pump...

Jeff