Running extremely rich? Fuel in lower intake plenum

[TKtw1nturb0]

I just did a fresh rebuild, car runs great but I thought I noticed a slight smell of gas in the oil, and i'm paranoid because of the fresh rebuild. So I checked all my vacuum lines and sensors and pulled off the upper plenum to check injectors and wires. Well as soon as I pulled it off, I got a strong smell of gas. Looked down into the lower plenum and I have rings of unburnt gas just sitting at the edge of each port toward the heads. I know that definitely isn't good...any ideas what would cause this? Also, pretty much a stock setup.

[TurboSinceBirth]

Could be leaky injectors dripping or not spraying a fine mist when they open up.

[fullracegt]

or o2 sensor maybe

[i3igpete]

FPR with ripped diaphragm will also do that. but it'll be REALLY bad, like car is nearly undriveable.