I have a 1995 4X4 3500 Long Bed Crew Cab Silverado with the 7.4 engine. The way this baby drinks gas you'd think it was Budweiser. Does anyone know of an after marker device that will mimic Chevy's AFM system? Can the engine be programed to switch from 8cyl. to 4cyl.? I know there are plenty of devices that will increase the performance but are there any that will significantly increase fuel economy. Cadillac had a 4-6-8 system a while back, I wonder if someone could figure out a way to get one off a junker and modify it for our beasts?