I have a 2150 carb on my 77 f250 4x4 400. My truck starts fine,choke, fast idle,curb idle,and timing all good,but when holding an even speed it acts like its starving for fuel,then when i accelerate it seems ok. any ideas? thanks

 

Could be some gunk in the jets causing a lean condition or the float level is too low. Could also be a partially clogged filter.