Question about using a cigar for smoke test...

So it's cold now, which means my minimal rough idle i've always had during cold starts is now pretty bad. I'm not getting any codes, but it feels like a misfire. I get consistant RPM (It's not bouncing around) but the engine shakes pretty bad after the SAP shuts off, and it goes away when after it idles for about 10 mins, or if I don't wait for it to go away, it smooths out once i put it in drive and actually give it some gas.



Anyways, long story short, i wanna smoke test it myself and i was gonna try the cigar test. Is it as simple as pulling air filter housing and taping off the intake hose and then blowing the smoke into the brake booster line?? I'm hoping it's obvious where the leak is, and hopefully something easy like the distribution manifold O-Rings.



FYI as preventative maintnance i've replaced upper/lower intake hoses, DISA O-Ring, Lower CCV hose to dipstick (Mine was busted in half at the bend like everyone elses), fuel pressure regulator hose and plugs (OEM). I know i should do my CCV, and i will eventually, i've just been putting it off because it passes the "oil cap off when running" test, so i'm assuming that means it's working, but i realize that doesn't rule out leaks. 108,000 miles on the clock.