The reason vacuum is used for advance is because depending on the load, the vacuum readings go up and down. You don't want the added vacuum under load, because it will detonate. And having the added vacuum while not under load will keep the plugs cleaner.

With a vacuum pump, it does not change when under load, it is a constant vacuum.

Allen Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first. Life was a little easier when I was just a wrench.