I have 2 codes P0171 & P0174. Oxygen Sensor? Top or Bottom?

Oh my goodness, those 20 items are not things to replace! They are "possible causes" of failure. P0171 and P0174 indicate that both "banks" of your V6 engine have oxygen sensors before the catalytic converters that are showing "lean" fuel trims. This means that there's a whole lot of excess air getting in somewhere -- either an intake gasket leak, a mass air leak, or even a mass air flow sensor providing faulty data to allow too much air into the engine and also the exhaust stream. Typically when both banks exhibit a "lean" code like this, it's indicative of a problem not related to the sensors themselves. Can you imagine both sensors coincidentally failing at the same time? Possible, sure, but extraordinarily unusual and unlikely. Testing will need to be performed. Please don't count on parts stores for much help. They are there to sell parts! Not give free advice as kindness. Which engine do you have -- the 4.0L V6 or 3.0L V6? The 4.0L V6 is known for having leaking "o-ring" intake manifold gaskets that can most certainly cause these codes. However, you should not just go replacing parts -- it's essential to actually see what's going on with the data and a physical inspection of the related components. PS - I live in Petaluma - hi neighbor! Good luck.