340 problems

I've used WD-40 to troubleshoot engine vacumn problems. While the engine is running, spray a little around suspect areas. Listen for any change in engine RPMs. Make sure all vacumn hose oriffices are capped. Your high RPM problem is a little mysterious. Vacumn leaks usually don't come into play at high RPMs. Distributor timing and carburation would be suspect. If you can get the symptoms at high RPMs with the car out of gear, try a dose of gas into the venturi of the carb. This may tell whether you have a leaning out problem. If all fails, I would resort to a diagnostic hookup at a good auto service facility. Just some ideas. Good luck. Howard