Bent Valve or Major Vacuum Leak

After making a pass at the strip last evening something wasn't right. No noises and oil pressure was fine. The motor won't idle down. Normally it idles at 1500 but last night couldn't get below 3000. My buddy took a rag and covered the carb opening. Then it idled down some. I've also been told that if you have a bent valve it could cause this. I would think it would be just the opposite. The motor is a 414 with Indy360 heads and the big block valve gear. Today I didn't have time to do anything with it except pull the valve covers. All appears to be normal there. Tomorrow I will run a compression test. Ideas, thoughts or suggestions? Thanks