[Es2] still having oil problem (kinda long!)

[Ben Klumper]

If you recall from last week, after start-up for the first time, I got an oil pressure warning light. When I checked the oil, it was foamy and full of tiny air bubbles. Well, I thought everything was fine after I checked the oil level earlier this week. The oil looked normal and was slightly below the full mark on the dip stick. So today, I fired it up again only to get the oil pressure warning light immediately, as before. Shut it down, waited a minute or so, and checked the oil again. Foamy! I'm at a loss here.
So I have two problems: 1) oil gets foamy very quickly. 2) oil pressure warning light comes on immediately upon start-up.
Are the two related? After today, I would say yes. I thought at first that the warning light may be due to an electrical issue, perhaps I connected something incorrectly. But I checked and re-checked the wiring from the sensors right to the Autocheck system and everything makes sense. I even switched the wires on the sender itself, but it also gave the warning and pinned the oil pressure gauge past 5 bar.
That's the other anomaly; through all of this, the gauge reads on or close to 5 bar. I believe that when all is well, this is a normal reading for the first couple of minutes after start-up. However, if the gauge reads fine, why am I getting the warning light? Conversely, if I'm getting the warning light, why is the gauge reading fine? Shouldn't it read lower than 1.8 bar?
Finally, what the heck is causing the frothy oil? At this point, I'm thinking it has to be mechanical. During the rebuild, the oil temp sensor and both oil pressure senders were never removed, thus I've ruled out incorrect installation of these components. Could it be the oil pump? It worked fine before, and it was properly installed (engaged with crankshaft) so not likely. What about the oil pick-up suction tube? Could this be clogged? Not suctioning? How does the suction occur? Is it directly from the pump, or does it work off the engine's vacuum? The crank case breather system is all brand new. What about the S4 windage tray? Should I have deleted the plastic baffle that is stock to the 3B? Is this causing too much resistance/not enough flow?
Sorry for the long ramble. It's mostly been me thinking/writing out loud. This project cannot progress until I find out what the cause of this problem is!!!

Thanks again for listening. I hope someone out there has some more insight!

Ben