My Rb20det Not Working Properly.

[Acen]

I'm not 100% sure but I've been reading some posts about cylinders going out because of spark plugs/coil packs not working and I just wanna make sure nothing serious is wrong with my engine. What I noticed is one of the blocking thing at the end of hose from my oil catch can disappeared and oil leaked out of it. I don't have a rocker cover so oil leaked into the coil packs area. What happens is evertime I start the car up on cold, it will sound normal and after I drive it for a little while like 2 minutes, sounds like one of the cylinders not working (boxer sound) and I lose power. Would it be a fair chance one of my spark plugs/ coilpack is just covered in oil and not working properly?