318 swap gone wrong?!
you said "new carb", what is the new carb? A new carb is not always good. In my latest 318 build I got a new Edelbrock AVSII 650 and had problems getting it to run well. It was good enough to get through break in, thank God, but it ran like **** at lower rpms. I took a known good carb off a different small block and all the problems disappeared. Got Edelbrock to replace the carb and everything has been fine ever since. Do you or a friend with a similar engine have a known carb that works well? If it's off a small block Mopar, it would only take a half hour to find out if the issue is in the carb.