vauxhall signum 2.2

[astonderby]

i have a signum 2.2 direct injection and i have done all of the valves and done the timing chain!
when the car is idleing it is fine but when i go up the road it starts juddering but only between 2000 and it will only rev to 3500 please can i have some help i am at my wits end i have tried everything!!!!