It seems odd that your wines don't clear. I have never racked a wine (at least in the last 3 years) other than off gross lees 2 days after pressing, nor have ever I fined or filtered. I always have very clear wine after 6-12 months in barrel. Many ultra premium wineries never fine or filter and many rack only once, or never in some cases (like Saxum). You risk stripping flavor and texture by filtering with a filter fine enough to remove the very fine sediment that is probably making your wine cloudy.
Sourness is usually caused by too much acid (malic, more often than not) or, as derunner said, small CO2 bubbles in the wine post primary or during MLF. Do you put your wines through and comfirm completion of MLF? If you made a dry red wine from wines that a not hyper fruit forward, you can probably taste some serious acidicty in the 8 g/l range for titratable acidity (TA)...compounded if there is malic in there. I am not too familiar with Sierra Foothills wines other than Naggiar, as my fruit is from Paso Robles. Rarely is there too much acid in Cab, Merlot, Zin, Syrah, Tempranillo, PS, etc from this area.
I think you should invest in a test kit to confirm your TA and S02 levels. Force it through malo ferm if you have not already. Just try to keep the wine around 65F or higher and free S02 around 10ppm (depending on the strain). A lot of people think temperature has a big impact on MLF but it is always dependent on the strain. I use Enoferm Alpha which will burn down to 57F, though it will complete faster if it is warmer (over 68 or so). If it is still too acidic, then you can adjust if needed after MLF by adding calcium carbonate or something like that. Just don't bottle for at least 3-4 months to give it time to work and sediment to settle. While I said I didn't rack, you may have to to remove more sediment. Tough to know for sure why it won't clear.
Anyways, I hope this helps and it's not a ton of information you already know.