What does the full readout temperature say when the engine is warmed up? I notice mine runs between 185 and 195 while driving, and considers this normal (center of gauge).

I also remember that on GM'* and most other cars, the A/C will turn on with the defroster to pull moisture out of the air, as it sticks to the A/C evaporator, this helps clear the windshield. It also could be that with air in the cooling system, the temperature sensor was not submerged and therefore not giving a proper reading. "It took forever to heat up"

In regards to it being sluggish on hills. You ARE running premium gas, right? If not use an octane additive. Also, if you haven't done so since buying the car, change the oil in the supercharger for good measure.

Temp. readout runs between 185 and 200 on mine. Thermostat in my car is a 195 so that is about right. I have always ran Premium in this car, BP gas mostly.

Just had an idea on the slow start, since you already found one bad vacuum line there may be others, I'd check them all. The computer does need a certain amount of vacuum reading from the MAP sensor before initiating spark.