Hello Forum, 1994 Suburban, K2500 7.4 454 146,xxx miles I am having 2 different issues. First, I am getting very bad fuel economy. 7 to 9 miles per gal. I am looking to upgrade my fuel system. I am wondering if there is an aftermarket system that can go on my truck or is it better if I switch to a carb system. Then I would have to change over a lot of electronics. Second, my speedo is all over the place. 2 speed sensors have been replaced already, by the dealership. For this problem I am stumped.