1988 Chevy Corvette Strange problem: white smoke, etc.

Hello, I have a 88 Corvette, with a remanufactured 5.7 L V8 that has 36k on it.
Out of nowhere, when I started it up one morning, there was Lots of white smoke from the exhaust pipe, since then same thing happens almost every time I start it, but the white smoke stops after about 5 minutes. I noticed it displays "Low Coolant" when the car is standing, but it disappears when driving the car. I put more coolant in, no visible leaks under the car. Also I noticed there was smoke and burning smell from somewhere under the right side of the engine on the passenger side, it stopped after about 30 seconds, only repeated once.
A few days ago the throttle would get stuck open every time I press the gas pedal, but ONLY when the Engine is On.
What could be causing the problem? Could this be an electric problem? Or one of the sensors?

Your help would be REALLY appreciated!