looking at a 2001 2.2 automatic vectra for a mate , it runs absolutely terrible & struggles to even rev high enough to change gear , will only rev to about 4000 rpm in neutral , even then it is spluttering & misfiring.
p1171 keeps coming back & in live data the lambda signal is stuck on lean & the voltage is only going between 0.00v & approx 0.35v , to me this would suggest either an intake air leak or lack of fuel pressure .
I have suggested he tries changing the fuel filter & also has a good check for any intake air leaks .
any other suggestions incase I might have missed something obvious ??