When I get up to 40mph and then need a little bit more power the engine jerks and judders as though it's struggling for fuel.
if I accelerate hard it judders slightly then pulls like a train.
No codes or warning lights.
any help appreciated

2.1 X Type petrol 2003/2004 Auto

 

Mike,
First off take a look for any vacuum leaks check out youtube for how to do this.
Also had the same problem and for some reason changing my battery fixed my problem but the battery was shot this also fixed the problem I has turning on and off "s" mode on the J gate.

 

Have checked for vacuum leaks etc.

No issues with S mode and starts first time every time even when left for a week so not sure about the battery.

Going to change the fuel filter and then see how it goes.

Thanks for the help