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1992 Sierra 3500hd 7.4L dually lack of power after 50 mph

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    • #759964
      CCM1350
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      I have been trying to figure this truck out for about a month and I’ve done everything i thought to check. 1992 Sierra 3500hd 7.4L dually stumbles a little bit 0-10 mph but from 20-50 mph you can still feel it pulling but once you hit 50 it will fall flat on its face and feel a lack of power after 50 mph. The only code it threw was a 43 and i repaired the knock sensor connector/harness. I have also repaired the Coolant temp wire as it rubbed through the insulation. It has new spark plugs and wires and the distributor rotor and cap look fine. Fuel pressure is fine. dropped tank still just to ensure it was not dirty there a small amount of dirt on the strainer and in the tank but nothing i thought would cause problems. Was starting to think maybe transmission as i feel it doesn’t shift right 2nd gear feels iffy to me. Any advice would be helpful i don’t want to just throw parts at it.

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