I think hotlines is trying to defend the TBI system, as its quite reliable and if everything is working good will yield the same or better mileage then a 4 barrel. the only reason to remove it is because you don't understand it.
first off let me say with a granny 4 speed and 4:11 gears your always going to get lower MPG then most of that era 1/2 tons with 2.7 gears and 3 speed auto/overdrive but lets see if you can get to the bottom of it...
so what have to done to the actual fuel management system TBI system to help with fuel economy?
have you done the basic tuneup recently (plugs wires, brass contact cap/rotor button and fuel filter?)
when you look down the throttle body at idle (750 RPM) is the injectors spraying or dripping?
have you replaced the coolant temperature sensor with every tuneup ($15 value) it needs replaced for the system to be accurate
do you have a check engine light code seen on the right side of the dash?
