Is lifters a easy fix?

Sure it can be fixed, but at what cost. Replacing the lifters involves removing the heads off the engine. If you are going to that extent with an older vehicle, your best option is to rebuild the engine or replace it with a used one to save on labor cost. You are taking thousands of dollars. For a 2003 Aztek, that is worth $2000 on a good day with the fixed engine, I would personally would not invest the money and start looking for a replacement vehicle.