Sounds like a intake gasket or heater hose quick connect has gone south. If the sizzling was from the drivers side just under the t-stat housing, then I'd suspect the heater hose quick connect fitting has rotted out and cracked, causing coolant to spray onto the exhaust crossover pipe. Check your oil and see if it's cloudy or milky in appearance. If it is, then you probably have the infamous intake leak that plagues all 95-newer 3.1/3.4's.