when accelerating the battery power dosent stay on as long as it used to

Question:

I have a Toyota Prius 2003 model when accelerating the battery power doesn't stay on as long as it used to. If going up a hill it used to kick in and help pull then going down or decelerating it would charge the bat. it is wanting to stay in charging mode longer than it used to. Where I was getting 55 mpg it is now down to 48 mpg. I have checked with a couple of dealers and all they can tell me is the numbers on the diagnostic comes up right so nothing is wrong. If I keep the accelerator moving just a we bit going up hill the electric will stay in, almost like the potentionometer is losing contact, can anyone help, or does anyone know what kicks in the electric motor is it electronic or a vacuum switch

Answer:

There was a bulletin regarding the pedal sensor/potentiometer. There are no vacuum switches involved...only sophisticated Nippondenso Control Modules.