This happened on my original 360 2bbl in my van. In 20 degree weather it would sputter when going slow around corners.

You need to pull the head IMO. Valve seals are probably shot. The valves are probably crudded up bad. Worn valve guides are often the reason.

"The only thing to do for triumph of evil is for good men to do nothing"

"NUNQUAM NON PARATUS!"