Throttle Position Sensor

What are the symptoms of a bad TPS? My car is hesitating under throttle. It's much worse when the car is first started cold. After it warms up it gets a lot better.

I don't usually take the advice of the service people from Advanced Auto but the guy there thought it was the TPS. I back-probed the TPS and it's putting out 5 v with throttle in the closed position. According to Haynes it should only put out about .5 - 1.5v in closed and 3.5 - 5v wide open.

Assuming it's bad could this cause my hesitation and stumbling on acceleration when cold started??

Thanks!

For the record, the TPS wasn't bad (at least as far as I know)... the hesitation was a burned out plug wire which had happened once before.