Since AMR won the bid in San joaquin county and took over EMS, I've lost track of the frequency also. I've tried all the AMR-west freqs. They opened a new dispatch center in Salida. I'll keep monitoring, and check with some friends at SFD.
Here in Modesto I have always heard AMR dispatch on 155.295. I am still able to hear them on this frequency even with the new radio system. They are probably multicasting on this frequency for some reason? I hope they continue to do this so I can still hear them.
AMR in Salida is using (as of about 10 days ago) the Fisher Wireless Passport trunked system listed in the California database trunked section for some of their company comms. See the "Stockton", "Bear" and "Oso" sites. They are dispatching some of the government fire agencies in San Joaquin and Stanislaus counties now so you will also hear them on the agencies' channels, too - usually only to dispatch agency units.