can a bad thermostat effect the way your car drives(performace wise)? thanks

 

yes

 

what would be the symptoms

 

stuck open - car runs rich a lot - bad MPG.
stuck close - engine overheats

 

How would it being stuck open cause it to run rich? Is it because the engine runs cooler (Or, in the case of my car, almost cold on the highway) causing it to try and heat it up?

 

engine runs too cold. it never reaches operating temp. car is constantly in cold start up mode...runs rich.

 

can it cause your car to lack power when it is warm, or even surge

 

Is there something else to hint you at the thermostat or are you stabbing in the dark? Yes, it should definitely reduce power if it's running rich but not sure about the "surging"... maybe. Of course if this is the case you should also notice it's taking forever for your car to warm up. Also there should be times when it runs fine, like when the thermostat SHOULD be open.

Either way I think it's time to buy or borrow a repair manual with a troubleshooting guide to help narrow it down - lack of power and surging can be lots of other things too.