I have seen a number of issues concerning the ebpv operating at the wrong time. I believe the only input regulating when the valve can be shut is the engine oil temperature sensor. Is this correct? Do these sensors occasionally go bad? If an eot sensor is giving bad information, it would affect the Exhaust Back Pressure Valve operation. That same bad information is used to control the engine resulting in poor mileage, low power, etc.

 

it was my understanding that the ebpv has a sensor that is right under the front part of the engine cover and has a tube running from the exhuat manifold to the sensor that decides the valve

 

I think you are talking about the exhaust back pressure sensor. I think (but I don't know) that it's signal does not affect operation of the valve. I believe it is only used for diagnostics. It can tell you that the back pressure is high and therefore there is an exhaust restriction (possibly a stuck shut ebpv).

 

AIT, EOT and EBP are all used to operate the valve...

It sounds as if your EBP sensor is plugged, and you may have unplugged your AIT sensor...