I have been getting an RPM related noise in front of the gas pedal of my '93 GMC 'burb for a while now. Today it got louder and the engine runs badly at the same time the sound changes to a 'bad bearing' noise for a few seconds. Would anyone agree it may be a bad distributor bushing / bearing? If so, what are my options? (Are rebuild parts available? Aftermarket?) Any other ideas would be greatly welcomed also! Thanks. Carl.