I searched back the last 6 months or so & didn't find any recommendations for diesel shops in San Diego (I have an '00 Excursion, with the 7.3L PSD). I saw a few recommendations for Bud's Diesel Shop, but that's a bit far away in O.C. At the Ford dealer nearest me (Mossy Ford) all the service writers have a terrible attitude & seem uninterested in helping, but the techs & service writers at the next nearest Ford dealership to me (Kearny Pearson Ford) are super helpful, seem honest & the service so far has been great, so I always take my Excursion there. The only thing they aren't too keen to work on are non-standard performance stuff (not atypical to most dealers), so I am interested if there is somewhere else local in San Diego that is better versed in diesel performance work & other non-standard mods?
Diesel shop just North of San Diego - Alliance Diesel 951.654.4320
Near Hemet / San Jacinto there is a new diesel shop. They work on Ford, GM, Cummins and many other brands. Took my F-250 there for a new engine, the dreaded 6.0L. They did some updates to the engine, EGR, water pump, head studs, etc.
Dave the owner was top notch, let me know w hat was going on with my truck the whole time and went over everything in great detail. Dave also works on farm equipment, class a tractors and he had a H1 Hummer there too, GM 6.5L Diesel baby!