i have an audi a4 2004 and the emmision light has come on and there is a loss of power.
the car shudders until the revs are high and also feels like a loss of power
Either a catalytic converter, lambda sensor or air mass meter problem, I guess. Having the vehicle scanned will show up where the fault is, as a fault code will be stored in the cars computer.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.