8.5 mpg help

[surfsup]

I’m getting 8.5 mpg , the motor is an 85 all stock with the exception of the exhaust, 2 ½ cat back, and a Mallory coil. Everything else is stock. 5 spd, 273 rear..This is what I have done to the car so far.
Replaced cap rotor wires plugs, cleaned egr plate, rebuilt carb, the only thing I changed on the carb from stock was the power valve, orig was a 2 stage, I put in a single stage 6.5.. Replaced all filters. All emissions are disconnected except for the egr valve. I have been over the motor several times to adjust the carb, reset floats and mixture, tried setting the timing at different degrees, nothing. If some one could maybe shed some light here on what’s causing this rotten mileage, would be great. I drive easy, no heavy foot.