why does it idle but not take fuel

I don't think anyone is telling him to replace a bunch of things at one time. Yes, the vacuum leak needs to be fixed. The engine will never run right until he does. It can also damage the engine and cause other issues like excessive oil consumption.

I left a plug out of the back of an Edelbrock carb once, and it ran exactly like you're describing. it idled fine, but ran horribly under load. Huge vacuum leak. Oops.

But there is no guarantee that it is the one item that will fix the problem. Others were just throwing out items to check if the vacuum leak wasn't 100% of the problem.