I have a 1990 Toyota 4-Runner which all of a sudden went up to the high (hot) side of the gauge. Never having a problem before, I assumed the problem was related to a stuck thermostat! Not realizing the thermostat was on the bottom of the engine, I went to Checkers auto parts and picked up a thermostat and gasket.
After spending Friday working on the getting the old thermostat out which was completed fryed, I refilled the radiator with Sierra antifreeze and distilled water. My wife was telling me when the car was turned off she could hear a gurgling sound!
Just tonight when coming back from a restaurant, I was keeping track of the temperature gauge and it started creeping up again towards the hot side of the temperature gauge. While going to the restarant I noticed no hot air coming out of the vents.
CAN SOMEONE PLEASE HELP ME SOLVE THIS PROBLEM-POSSIBLE BAD HEAD GASKET OR HEATER CORE????? ANY MASTER TECHS OUT THERE WHO CAN HELP ME NARROW THIS PROBLEM DOWN WOULD BE GREATLY APPRECIATED!!

Sound like you have an air pocket in the cooling system. That will cause the gurgling/no heat/etc. problems.

Parking the truck so the front end is uphill, remobve the rad cap, and let the engine run till it warms up and the t-stat opens. Also set the heater temp to HOT. The air bubble should work it's way thru and out the rad.