2004 2.0 D4D losing power

[marshallshingirai]

Hallo everyone.

I have 2004 2.0 d4d avensis which has done almost 160k, bought second hand and driving fairly well until recently. It all started one day doing normal city driving all of a sudden upon accelerating to overtake the vehicle suddenly lost power and and engine check light came on. Took it to an auto shop and the and it came out with error P1251, like wise the mechanic advised to change the Vacuum switching valve and we did. Cleared the error codes and drove again. It did not do five miles before the light came back again with the same error. Checked to see if the turbo wastegate was stuck, was not but cleaned anyway, checked the and Cleaned the EGR as well cleared the errors drove for a short distance same error came back again. Are we missing something, can this error emanate from elsewhere besides the vacuum valve.  I mean an electrical fault or something else. I am really running out of options. The 

[frankie406]

Check air and fuel filters. Any split hoses, dirty injector,intercooler or air in the system try bleeding it.

[marshallshingirai]

Hie frankie 

Sorry i neglected to say recently serviced, i probably need to look at the injectors, also at around 3000 rpm is when you feel the engine drag and lose power again the same error cod keeps coming up. P1251.