Hi 3ring. Your grinding out back, especially with the no-ebrake, is almost surely destroyed e-brake shoes. You may even have broken hardware hanging up inside the disc hub.

On your injection issue, sounds like it's time to take it all apart. I would say you either have a problem with the metering unit or the fuel pressure regulator unit is shot. The metering portion is the little metal plate that floats up and down to measure air flow. This is right above the black rubber ...what... sock? that brings the air in from the filter box. I've seen them filthy and corroded inside and unable to respond smoothly. The FPR is a larger and much more finicky unit to break down and repair, but it can be done. They are prone to clogging from all sorts of debris getting through bad filters and such. This is the part immediately aft of the metering unit. Look for the multiple hex fittings on top.

DS