Mechanic did not say anything other than he couldn’t figure it out.
Meanwhile back to California for me. Again car is fine at high speed. Began noticing in bay area at low speed more frequent instances of loss of power when starting up from stoplight etc. Day before I had to head back to Iowa I suddenly noticed new sound from deep under hood - periodic but some highs were higher than others. Old mechanic happened to be a few blocks away in San Francisco so I pulled up. Sound died just as I did!, but sound came back after 5 min (prob same sound but I was no longer in car). Can’t tell if its metal versus metal or air noise or what. Mechanics found 6! codes (all the old ones I guess did not get a list) including what seemed significant to them a catalytic converter code. They added oil and listened to engine with stethoscope. Nothing. Turned off engine, jacked up front end, and slid under with hammers to tap on things to try to recreate noise I guess. After 15 min they said “I don’t know what to tell you”.
So that’s the third time I have had to abandon repair to drive 2,000 miles! Again car just fine at high speed. One stop for gas the engine had that new sound again while stationary after I pulled up to the pump. Once above say 20 mph no sound and smooth sailing. Since then occasianal loss of power when starting from stop but that new noise has not come back. Just now scan tool shows P0171 and P0420. I should email old mechanic to get those codes. Car is going to sit awhile I deal with other problems.
Exorcist next step?