P0302 cylinder two misfire

One guy said me it can be a vacuum leak even at the intake manifold's gaskets, the rubber sealings can be already worn, since its a 16 years old car. And also that might be why after the change of the O2 sensor its worse now, because now its monitoring properly, and now like every second its a sputter on the exhaust, while its been like 3-4-5 seconds with the old O2 sensor.

That's why I said smoke test it pin points leaks

I've been searching for a picture of an AZD engine Golf 4 (thats not mine, but im not at home, cant make a picture of it), and I'd ask again, which hose should i blow with smoke. Atleast i want to try with cigar/vape, i know its not so exact by that, but worth a try.

Where the booster hose attaches by the throttle body.Your brake booster hose could be cracked as well

Thank you, I'm not home and im not with this car now, and I'm going home only next Thursday, so i can check only then. Also as i've said, its not a picture of MY engine, and the brake booster hose is which i've replaced already.

OK so you want to put the smoke in where the brake booster hose attaches to the engine.