Not a stang question...but still ford...360 help

[freak007]

hello,my parents own a 76 ford PU with a stock 360 2bbl and a 4 speed,it had'nt had a tune up in years,and was only getting 8MPG,so I gave it a tuneup,new plugs,wires,cap,rotor,and timing,I did not replace the condensor,when I did the timing,it had been off 4-6 degrees,the carb had been tinkered with too,the accelerator pump rod was in the top hole,I moved it down a hole to where it is supposed to be,before the tune up it would miss BAD from 40-50MPH,once past that rpm it got better...

before if you were downshifting,in a corner and stomped on it comeing out,it would stumble...now it burns the tires...it still stumbles at 40-50,but not as bad

my problem is it now gets only 6 MPG...
I need to know the "best"place to set the timeing for mileage and power,also the easiest way to adjust the carb,and why is it stumbleing...