With the low octane fuels today, I doubt very much that it is a vapor lock problem. I do run my 235 very hard at time, even close to over heating it, but it never tried to vapor lock. It was rather common in the day but not much now days. I would also look for an ignition problem,
Scott


Scott Ward

2 1948 1.5-ton Loadmasters
The red one and The snow pusher
1 1950 3100
1 1955.1 Chevy 6500
1 1954 Chevy 6500 2-Ton
1 1955 1st Series COE 5700
1 1963 K20 (454)
1 1964 C10 (350)
1 1951 1.5-ton Dump Truck
1953 and a 1956 Ford F800

Raising a teenager is like trying to nail Jello to a tree!