Service Engine Soon light on, power loss

Ok, so I started my car up lastnight on the way to my friend's house and my service engine soon light came on. I turned it off and started it up again. Still there. So I drove it and noticed a huge power loss. It does not accelerate to it's full potential and it even seems a little less "ballsy" than stock. I have a CAI installed and I checked all the connections and everything seems tight. It kinda has a whistle that sounds like it is coming from the front driver side. My buddy thinks it might be the torque converter or a head gasket. It also seems to shift a little tight and could possibly use some transmission fluid. How do I check the tranny fluid level and where would I add more if needed? I can't seem to locate the damn thing. I also noticed some oil that seems to be leaking from the manifold or the cylinder head. Has anyone had similar problems with their cars? Anybody have any ideas of what it could be so I can save myself some time and money in the process? Thanks in advance! -Dan

OK all day brainfart. Can't be the torque converter because it's a manual. Don't know what I was even thinking when he said that lol. Any other ideas?? Thanks, -Dan

First thoughts and cheaper repair ideas I have are plugs and wires, pvc valve and oil filter. Since the car isn't really that old (roughly 23,000 miles), I would think if there was a major mechanical flaw, then there would be a recall. I'm doing alot of brainstorming and this is driving me crazy!!! All ideas welcome. Thanks! -Dan

Did you scan it for codes?