Q: vacuum leak

Hi,

I recently installed an aftermarket cold air intake and tuned the car. I have had many occurrences of code p0300 and Bama tuning recommended I do a crank relearn which I did.

I also sent BAMA a datalog afterwards and they said I might have a vacuum leak and my car is correcting 10% (and something about fuel?). They said at idle, I'm running lean.. They suggested a smoke test. Since the car is only a little over a year old and I purchased it brand new, does a vacuum leak sound reasonable? Any suggestions on proceeding with a smoke test or other methods of diagnosis? Another mechanic said he thinks the "leak" is due to the plastic tapered tube part of the cold air intake and tightened it up well.

My car has 16500 miles.
My car has a manual transmission.