If your fuel pressure guage is near the carb or anywhere near the engine where heat will effect it-----it won't be consistant and/or accurate--------you will only rear pressure that the needle/seats hold closed and it will read less where they are passing fuel-----try setting the pressure down to 2 or 3 lbs and see if conditions show any improvement------also try shutting pump off and see if engine runs better as it clears up.

and 40 degrees timing in todays PC homofuelinjected day is crazy

Can you post some pics of pump, carb, fuel lines around carb, lower front of the block, tank fill neck, vents????????