I have a 94 Sonoma 4.3L TBI 5 speed 4X4, that is spewing black smoke out of the exhaust. Sometimes it will stall and I can only get it restarted by pressing the gas pedal to the floor. There are no codes or I should say there is no check eng light. I have been reading about this problem and get too many different answers to even know where to begin. Looking for advise.