Vacuum Leak After The Carburetor Tuneup

[NRX]

So I went to get my car's carburettor tuned up the other day and the mechanic checked the plugs, removed the air filter and whatnot and looked in to the carb. After inspection he said that my carb doesn't require a repair/tuneup as everything seems to work in good order ( Save for the low fuel economy) and he said the car also responds well to fuel/air mixture adjustment. Then he fitted everything back and I happily came home.

The next day roughly after 30Kms of driving when I was coming home I could smell a strong petrol odour inside the car ( I was driving ). I was close to home and after stopping the car I tried opening up the hood and felt the same petrol odour. The next day I removed the air filter and the the strong petrol smell was still there. I started the car without the air filter and I could hear a hissing sound from near the carburetor, even after I fixed the air filter it was still there but the sound was lower, also I noticed the breather hose ( the hose that connects the top of the engine to the air filter element) was split near where it connects to the engine head. But I don't think it is an issue since the sound was there even when I covered the hole tightly with my hand .

Then I tried applying brake when the engine was idling, guess what ?? when I take the foot off the brake pedal the engine RPM dropped and tried to stall , it gets worse if I pump brake. This issue wasn't there before I took my car to repair the carb. I could hear a small hissing sound when I apply brake too, I don't see any damaged or loosen hoses apart from the breather hose which I don't think causes any vacuum leak.

What could be the issue ? Is this some sort of a vacuum leak ?

The braking power is same as before by the way, no issues.

P.S: The petrol smell came again yesterday when driving, but it went away after about 10,15 seconds

Edited January 17, 2012 by NRX