Gas vapors expell out of carb for 10 mins after i shut the truck off. This goes along with my other issue i guess. The engine continues to start and idle great, but it will not handel an acceleration from the throttle unless you increase the throttle very very slowly, and then it does want to regain idle for a couple of mins. Its an inline six 65 chevy. I just bought it and it ran perfect for the first 45 miles or so then with out any changes to the truck it just cut off after shutting it off for 30 mins to go into a store. The truck made it 30 feet and quit responding to the throttle and shut off. It happend without any pre warnings. It did not show any signs there was an issue, not even a noise difference or drive difference from when i turned it off to go to the store to strating back up to leave. Some people have mentioned maybe its a stuck valve, but it hard to believe it would be that with out some sign, at least a small one. It was running perfect. Thats what made me think maybe a carb or vacuum issue. Here is a list of my trouble shooting and the stuff i've done so far. Also, i have a glass fuel filter and i see that it stays full of clean fuel so i dont think its a clog or the fuel pump.

1. I put a new carburetor on it
2. 6 new spark plugs
3. new fuel filter
4. distributor looks good
5. distributor does not have a vacuum hose port
6. the carburetor has a vacant port next to the fuel/air mixture screw that makes a sucking sound when running, but there is no where to run a vacuum hose that i can tell. I have tried plugging the hole but it makes no difference in condition.
7. when the throttle is pushed at normal or fast speed it makes a giant air sucking noise and spits blacksmoke out the rear.
8. i pulled the valve cover off and the rockers look good.

please help

It's better to have it and not need it, then it is to need it and not have it. "Woodrow F. Call"