where is the o2 sensor a '94 VE motor located? At 106k, could this be the cause of my power problems and crappy mileage? I know VE's are hypersensitive to bad sensors

 

clarification: the car is fast as hell until the engine hits "closed loop mode", when the coolant reaches full temperature and the ECU starts reading the information from the sensors. Then, sluggish and unresponsive - the longer I drive, the worse it gets (sometimes). Cold weather doesn't make it better, it just delays the point where the coolant temperature is such that the ECU begins to collect sensory info.