Thanks for your help Nuzza. I'm not exactly sure what you described is what was goin on with mine. You did put me in the right direction though.
So armed with a LED flashlight I found the giant sucking sound. Turns out it was a pretty well hidden under the gas take, in between and in front of the cylinder heads (sort of).
Here's a wide angle shot to get oriented.
Here's a close angle to get a better look.
Just thought this may help someone else with the same problem.