i have an 03 silverado with the 5.3 engine. whenever i kick it down the check engine light will come on. it says that all 4 02 sensors have low voltage. well i checked the fuel pressure and i have 45 while idling and i'll get around 55 when i kick it down going down the road. is the fuel pressure the problem? what is it suppose to have at idle with the regulator hooked up?