I took off my upper intake manifold to have it powder coated and found a puddle of oil inside the intake. Where would it be coming from?

 

PCV valve hoses suck the oil and vapors in there.

 

i was wrong ...go figure

 

that should have a baffle on it therefore it shouldnt be sucking up oil, I bet coming from the pcv sucking it through the intake make sure you have a crankcase filter below the pcv

 

It's fairly common and as stated before, it involves the PCV system. There are things you can do to help the issue. Most of the solutions are free or very cheap. It all depends on how bad it is and how much you're worried about it.

Even with baffles some vapor can get by and over time would cause this to happen too. But again, not usually a big deal unless there's a lot.

 

Are you sure that it's oil and not goo? It is normal for there to be a certain amount of goo in the plenum after a long period. It is not necessarily oil, rather it is just fuel vapors that turn into an oily coating. It doesn't hurt anything as long as it is not coating the TB or the intake runners to a thick layer.

You should, as a matter of periodic maintenance, use a rag coated with a little carb cleaner to keep the TB blade and surrounding areas clean. Failure to do so can result in poor idle quality and a sticky throttle which is more of a problem with a stick shift car.