Why does oil pressure keep being low?

What is your question?

I have replaced VTEC solenoid (which comes with switch). I replace my oil every 3000 miles. Sometimes my car works fine and the engine light shuts itself off. Other times, there is a tinny rattling noise in engine and absolutely no power. When the engine light isn't on, there is a ton of power. I have to shift down to go up hills (more than reasonably so, and only when light is on), but I can't shift as low as I want because when I approach 3000 rpms, it goes into "limp mode" and I REALLY don't like the jerking feeling when that happens. Last time I got codes run, they were p1009, p0116, p2646 and p0011. It has shut the light off itself after oil changes, after getting gas filled, and just at random moments as well. The engine light always comes on when I am going up a hill. I have only had this car for less than 5000 miles and already changed oil twice and replaced solenoid. There must be something BEHIND this issue.