i have a 1406 600cfm carb on my 350. it was running perfectly.i cranked it up one morning, pulling out onto the main road ,i gave it some gas and it poped through the carb. i got to the red light and noticed it wasnt running right.pulled over and found that i had a vacum leak. went home ,and checked around the intake and carb with starting fluid and found it to be around the carb. changed out the base gasket and still had the same problem.i took the 600 off and put a 750 that i had on it and it runs like it should.i took the 600 apart but could find nothing wrong the gaskets didnt have any signs of leakage. has anyone had this problem? is there anything inside that might have gone bad?