This is no joke, I can,t fine where my thermostat is in my 1997 merc sable, ,i even followed the top hose back to the engine block

If you follow the "upper" radiator hose from the radiator to the engine it should have a metal piece that bolts to the car ( usually with only 2 bolts) and also the hose is clamped to it. it most likely has a domed shape to an elbow looking piece. take the "upper " radiator hose from where it connects to the engine. remove the bolts that hold this metal piece to the engine that you just took the hose off of. the thermostat "should" be located under this piece. you must take that metal elbow thing off from car to access the thermostat. where it bolts to the engine it most likely will have only 2 bolts and where that connects to the engine will be a gasket and it will be kinda football shaped. a lot of cars will also have a brass flat screw on top of this domed shaped elbow. that will be the give away to that that is where it is. what you do is when the car is running and the coolant starts to get warm, you back out the brass screw a little. this will let the air escape thats trapped and when coolant starts to escape tighten the screw back down. now you have the air out of the system after youve replaced the thermostat. I hope this helps....