j2k2x

I've just completed an engine swap, the engine out of my wrecked S4 into one that had a bad engine. I had driven the car perhaps 20 miles or so with no warning lights but a significant oil leak. It was coming from the upper oil pan that I have switched out. Now there are no leaks but I get an oil light.
- the car will idle (for up to 30 minutes) with no light. But once you give it gas to about 2000 rpms the light will come on. Turn the car off then right back on and there is no light for as long as it idles. 105k miles, moble 1, oil pump intake isn't clogged, o ring seals on the pump are good. No leaks, brand new sensor, I've even swapped the wire from the oil pressure sensor to the plug that is next to the power steering res. what should I try next?