A quart a week? You may wanna check and clean your CDR.

Stock gauges aren't the greatest to rely on. You said there was a knock but by the time the oil pressure did come up the knock went away. Could be a leaky injector causing a knock, and the oil pressure sending unit going bad? Coincedence maybe?

Change your fuel filter, top it up with Diesel Kleen, start 'er up, let 'er run for 10 seconds. Shut down and let sit for a couple hours, even over night if you can. Then drive it like you stole it.

You can do the same thing with Auto. Trans. fluid if you don't have Diesel Kleen.