72 360 first start question

Well, when i had the TDC incorrect (10 deg. After TDC) it ran screwy in that. I could get it to run but only with lots of throttle and advance. When I was using that as my starting point I set the initial timing very way from !5 deg. after TDC to 15 deg. BTDC and it would basically run the same. If the throttle's pegged it'll run ad sounds good but if i reterad it or idle down it dies... Now that I've found the coorrect TDC nothing has changed. I set the initial timing (15 deg. BTDC and ATDC) according to the new (factory zero mark) and it's same ****. Also when I fire it at any settingthe throttle revs then after a few minutes mellows which makes me think vaccuum leak.