Thanks for the reply. If I had to guess, the valve/flap may have stuck closed because the car can’t climb any sort of grade or get up to highway speed.
It strikes me as odd that the dealer had this vicinity open to install the “Motor AY Intake Manifold”, which they say they broke, after which they said they tried again to replace that same part (check engine light was still on so they pulled it and reinstalled the old one). Between the head gasket work last year and the dealer service, no one noticed that it needed to be cleaned earlier? Hmm… (Dealer wants $800 to clean the manifold but shop that did the prior work still stands by their faulty ECM diagnosis.)
The shop we used for the head gasket work last summer and to repair the shorted headlight assembly either had very bad luck with our car or was dishonest (took us to the cleaners). The first HG repair failed immediately, bending valves (re-do of the job was under warranty). When the car was supposed to be ready for pickup, we learned the rack-and-pinion is leaking (to the point of fluid accumulating in the exhaust and rising up through the engine bay as smoke — not something that had occurred prior to the HG work). When the rack-and-pinion was repaired, we took it on a test drive only to find we couldn’t make a turn without the car shaking/quaking (formerly it had no odd vibrations and had never been in a serious accident). That was diagnosed as a bad drive shaft. While that was being repaired, a CV boot was apparently torn (just had those boots replaced about a year prior to moving into the area so it didn’t add up). Then, as if that was not enough, the muffler started whistling — high pitch, annoying sound — every time we would reach highway speed (this is all before we even managed to get the car home from the shop last summer). Needless to say, it racked up a ridiculous repair bill. (Previously we had the same mechanic for ~20 years — never had anything like this happen.)
While I wish we had obtained a second opinion sooner (on the prior work), most likely that would have meant taking it to Subaru and as this year’s experience has demonstrated they haven’t been much better. In February, we even called on Subaru of America as this is our 2nd Subaru purchase (customer loyalty?) but they gave us odd explanations about not having any master mechanic in their employ to advise the dealer (the out-of-area dealer that sold us the car told us otherwise by phone). SOA also claimed they couldn’t compel the dealer we are currently stuck with to send over our service records (we requested they review the records, if nothing more, but they claimed the dealer had no obligation to comply with their service records request). All the way around, our experience has been bizarre. (Not even the pandemic situation can completely explain it.) I’d be thrilled if it could be as simple as buying a spray-on type cleaner and unsticking the flap/valve. But if that is all there is to it, one wonders how this solution eluded two different repair shops. 