[MuseChaser]

Tell them, in no uncertain terms, to check the direct injectors for leaking. The injector seals should be replaced whenever the injectors are removed, and shops don't always do that. That could cause exactly the symptoms you're having. ALSO.. have them check the valve clearance adjustments. Some techs tend to adjust them towards their tightest tolerance side, thinking they'll get better performance. NO. These engines like them in the middle of the adjustment range.

How do I know this? I went through EXACTLY what you're going through, and my Toyota "Master Tech" got both of those pointers directly from Subaru... and it solved the issue.