At first i'll say sorry for bad english, as i am from norway :P
But i have a problem with my astra mk4 hatch! it's a x14xe engine.
when i put the "pedal to the metal" mostly in second and third gear, it's a bit laggy. Sometimes it's smooth and somtimes it laggs like hell.. what do you think the problem can be? air mass flow meter? lambda senson? If someone have experienced this before i'll be glad for som tips