Finally,Service engine light on!
 

99 gmc 6.5 turbo 3500,200,000 miles.
Had the code read and it said ecm has detected a fault in the map sensor with a probable cause of intake manifold fault condition?Someone please tell me if they are referring to the pmd or what???.I have replaced:bat: the turbo boost sensor.The condition of the engine is black smoke on take off ,lack of power,eratic idle and sometimes will race 5 ,6,thousand rpms on a touch of the pedal.Has difficulty holding steady over 50 mph.