I have a 2001 F-550 w/7.3, started it the other day, service engine light came on, runs rough, no power, top speed of about 10 MPH. Found the harness on the right bank was fried and # 1 injector on the passenger side was bad. Replaced the harness and the valve cover gasket, Cranks up but runs extremely rough. You can unplug the #1 injector and it runs pretty good on 7 cylinders. As soon as you plug #1 injector back in, kills the whole right bank. Checked the engine harness, took the Injector driver out of my 02 350 and put it in. Same problem. Runs good until you plug #1 back in and you lose the all 4 cylinders on the passenger side.
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