I get a check engine/reduced power warning when I really get on the throttle. Low boost. Searching lists a number of potential sources, but also a number of different presentations. Idle is fine, and I wouldn't know anything was wrong during normal driving. I've gotta get on it for it to happen. I'm planning to replace the vacuum lines because they're cheap and it's time ('08 w/ 95K miles), but I'm not familiar enough with the systems' function to know if that's actually a likely fix. Is there anyone more familiar with the induction systems' workings that can point me in the right/most likely direction given the presentation?

 

Do you have any wastegate rattle? I found that when my wastegates were shot I would get a 30FF when I gave more than 1/2 throttle around 2,400 RPM. Sounds like that could be your highway speed?

 

No rattle that I've noticed, and I'm the sort that notices that sort of thing for sure. Mine is RPM dependent; speed doesn't matter (though I've never done it in neutral or anything like that).