Brownie

Need help,I was reading about running the diagnostic on the ecu and so i decided to check mine out.Bear in mind I was not aware we could do this prior to coming to Yotatech.Anyways I got a code of 51.Can someone help translate.I have notice my gas mileage has dropped off over the past couple of weeks since i installed new plugs,wires,distributor cap,and rotor(go figure).prior to my recent installations i was getting 21mps on the highway.I have a 89 p/u 22re with 231k miles.
was thinking maybe time to take to a certified mechanic.advise appreciated!!!!!

jason191918

http://personal.utulsa.edu/~nathan-b...26diagnosi.pdf

See page EG1-115.