Gas sender unit

[JAM1777]

Hi,
I have a 1969 chevy C10 longbed. I have had a problem with the engine bogging down at freeway speeds and as soon as I get into the slow lane and speed drops to about 40mph the truck starts picking up speed again. I have put in a new chevy performance 290 crate, i have rebuilt the carb, I have installed a new fuel filter, and installed a new msd streetfire distributer. I'm running out of trouble shooting ideas and its driving me crazy. the one other thing I remember is when I bought the truck, the gas gauge was working most of the time and slowly stopped reading.....so my question is.......if the float on the sender unit went out, would that cause the filter sock to drop and stay at the bottom of the tank and get dirty enough so that at freeway speeds my truck would bog down and act like its not getting gas??? Does anyone have experience in this same issue?? any help would be very appreciated