it could be loosing vacuum, its the vac line that comes off the top of the super charger, then to the pass side fire wall, down the fender to under the fuse box area were some cars have a T, one side would go into the cab via that cluster of wires, and the other side leads to a vac ball in the driver side fender, under the head light area. ( some cars dont have this, some do) but they all lead into the cab from under the fuse box area.