[aeontony]

Spray some carb cleaner around the lines and see if you see bubbling..or maybe even just one outright unplugged.

As for the check engine light...I can venture a guess and suggest you replace the O2 sensor, but not until you find out what code the computer's throwing at you will you quite know what it's complaining about..even then it may be another item that's causing the malfunction. Doh. These things are a pain.