My 96 blazer (202,000 Miles)has been idling rough for abouta month now and has black carbon on ground from the exhaust. I been reading these posts for awhile but just joined today. It has been helpful in me trying to pinpoint the problem but I still have these issues. It idles rough nomatter what the temp is outside or if truck is hot or cold. It is also throwing the DREADED P0300 (multiple cyclinder misfire)code also. I have read over and over againthe DREADED P0300 Longpost. I have replaced the cap rotor which needed them bad since it was the stock ones on it. I put new plugs wires on it also. MyBlazer was backfiring hrough the throttle body recently untilI performed the following tasks I have taken the EGR valve and cleaned it and the port in the engine block. I took the Idle Air Control Valve out and cleaned it also. I also cleaned the Mass Air Flow Sensor. I ran a two stage fuel injection cleaning system through it(Golden Touch). I just ran some Sea Foam through it on Sun. When running this system cleaner through it seemed to run better for a short period of time. I was out today looking at it to check over some other stuff I read on here and noticed there is also coolant leaking from it. The intake manifold gaskets were replaced about 1.5 years ago. Has a new fuel pump and filter also. As far as I remember reading on this forum noone has really pinpointedthe problem or I may not have read that post yet. I need help before I put a rag in the tank and light it and claim the insurance money j/k

 

The fuel spider was bad and th water pump. Took to shop and runs almost like new.