Where exactly is it leaking from? On the passenger side of the engine, above plug #5? If so, then yes it is the infamous oil galley plug. The pressed-in soft aluminum plug eventually backs it way out of the engine, and if you don't catch it in time, you get to buy yourself a new engine.
Join the 3FE list, there are LOTS of posts on there on how to fix it. I've watched 2 being done, finally did one myself for a buddy. Not too hard, you just have to be careful.