I've got an 302 (carb w/ mechanical fuel pump). At approx. 3200 to 3400 rpm it goes to spitting and sputtering until I shift gears or slow it down. The car was a 4 cyl but somewhere along the way, the 302 was transplanted. It sounds like it's choking out but there is no electric or manual choke and the choke flap on the front two barrels is positioned to where it does not move. Carb is an Edelbrock (pn 1405)