Here in the Twin cities, we have an excellent dealer - Borton Volvo. When I asked the service manager about the lack of 240/700 in the parking lot, he stated that he discourages people from bringing older cars in. He explained that his mechanics were no longer good at servicing the old cars, most of those mechanics had retired and the newer mechanics think that 850s are old cars. Besides, Borton does not store a lot of parts for older cars and people do not like waiting 2 days while their sensors are on order.
That is why I suggested you email Rule 308. Fountain Valley is off the I405 northeast of Huntington Beach, at least an hour's drive from you. He is familiar with 760s and would at least be honest. He is also much cheaper than any dealer. Perhaps you could combine a visit with a shopping trip?
Us fortunate folks who do not live in CA or New England do not have EGR systems in our cars, so I cannot help you there.

Klaus

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1975 164 w/174,800mi (Sold) 1995 850T w/91,000mi, 1998 V70R w/129,000mi