REPLACE your entire set of vacuum lines with OEM new. At this age, you need to also replace your factory boost control solenoid and get a new Denso MAF (you can get this off amazon). Do this and then you will KNOW your system is great and it likely will fix the issue, if not you can stand on a high mountain knowing what is new. I have an 04, these things need replacement, not check as they all can look and feel fine but actually not be.