Fuel filter?

When I'm driving sometimes it's cutting out like I'm going to run out of gas. I filled it up with gas and it ran for three days with no problem, on the fourth day it seem to start again but then it started running good again
. Was wondering if it's the fuel filter. I went to auto zone to have it hooked up and they told me it was a vacuum leak but didn't understand how it could run for 3 days with no problem. Could you please give me some advice about this issue. Thanks