Engine Mechanical problem
1998 GMC C1500 V8 Two Wheel Drive Automatic 156000 miles
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when truck is cold starts run great, but after 30 minutes of driving starts to run rough. engine shakes, black smoke when you get on it. engines pop after it gets hot. maf,running rich, air chager,ect. but next day when start codes go away till you get on it. no oil in water, and no water in oil. runs great for 1/2 or so. but when get hot hard to start. when cold starts as soon as you turn key. ive done complete tune up,replaced o2 sensers,replaced aor charge senser,replaced maf senson, and had fuel system cleaned please help. its been to shop 5 times in the the last month. there at a loss. they told me they get misfire code, but i think there lieing. ive never seen that code pop up. its always the same codes listed above