Pontiac Problems? Ask a Mechanic for Answers ASAP
You didnt mention which engine you have. On the V-6, the t-stat is under the throttle body, behind the exhaust crossover pipe. Remove the 2 13mm head bolts, and swap in the new t-stat. Make sure after reassembly, to bleed the cooling system. Their may be a brass screw on the top of the t-stat housing, and possibly a second one on the pipe at the top of the water pump housing. Open the screws until antifreeze comes out, with no air bubbles.
If you have a 2.4 4cyl, the t-stat is on the bottom of the engine. You'll see a black pipe that wraps from the bottom of the engine to the back of the engine, at the water pump housing. Where the pipe attaches in the back, that's where the t-stat is. Pretty self explanatory once you see it. Once you replace it, run the engine until you have good heat blowing form the vents. Topping the coolant as necessary.
I'm sorry that your not satisfied, but as a technician who does this everyday, that is the procedure I use. After removing the air inlet duct, which is obvious, I get right to the bolts, no more, no less. It's not the easiest job, but that's the procedure. The only items I failed to mention from the GM service procedure was to disconnect the battery, which every procedure starts with, and obviously not necessary, the air duct which is obvious, and to remove the coolant overflow tank, which is not necessary. The labor time on the thermostat is 1.0 hour warranty time, and 1.4 hours regular book time. This includes bleeding the system of air.