would appreciate any help.1985 1300 voyager dfi. bike is braking down sometimes. next time you start it its fine. bike has all black sooty plugs.no codes on computer. fuel pressure is 32 to 36 when cranking on throttle.fuel return valve to tank seems to be clear and working. 13.7 volts from battery.on pluged temp,and vacuume sensors while running made a diffence for the worse . and temp sensor showed a code while unplugged.