Surging Idle and Low boost Issue
2003 Subaru with 170,000 miles on it. Don't drive it much these days, just on weekends. Was running great until about a week ago when the idle when warm the engine would surge a bit, maybe 100 rpm and the vacuum would jump from 18 inHG to 14 inHG, back and forth. At first the car still drove normally. Now I can only hit 7 PSI of boost, so only getting wastegate pressure. There is a hesitation when it revs off idle too now.
My guess was a bad vacuum leak (I think 20 in hg is normal), but i can't find anything, none of the lines look bad. I know i have the 'pill' installed. I did have an aftermarket BPV installed but replaced it with the stock one, no help. I reset the ECU but no help.
There does seem to be a noise coming from the intake/TMIC area, possibly a leak, but the hoses are in decent enough shape.