I just got my car fixed and bought the street avenger 670 carb well I put it on adjusted the floats etc.... and took it up the road and it seems to start surging below 2200 rpm or when i steadly keep it at like 3000 in any gear and when I cruise around for along period of time and I nail it,it starts poping back and then takes off. So instantly I thought it was running rich. So i took my spark plugs out and they were light brown to sort of white. So what is my problem, could it be my ignition? I have the Crane HI-6 and Crane distributor that has the mechanical and vaccum settings but I went be the papers and when i first crank it up in the shop and let it get hot it has amazing throttle response and sounds healthy but when you go down the road and cruise around it starts the surging and popping when I nail it. Please Help