Engine bogging.

[az1970k5]

I have a 1970 with a sbc 350, new, HEI, rebuilt quadrajet (electric choke) from National carburetors, new fuel pump all the way to new lines and gas tank. My truck starts on the first try even in the cold, it idles smoothly and drives perfect at first. When it gets hot or at operating temperature, it starts to bog down at stop and go traffic. Not all the time but most of the time. If I floor it I can keep it going, if not bogs down and wants to stall. It has never stalled, but sounds like it will. Also at higher rpm when kicking into the last gear it bogs down until it finally kicks in. Again, this is only when hot. It drives perfectly the first 10-15 miles or so. I have replaced everything. Could it be a bad carb or distributor? Both are either brand new or rebuilt.