Intermittent Bogging out

[Porter898]

Hi my Impreza 2.0 litre non turbo when I'm driving it pulls back sometime also when I pull off I have to put the throttle down really slowly to get the revs up and some times the revs want build up at all 

I am thinking it could be the map senser but not to sure.

any help would be much appreciated 

 

thanks in advance 

[Phillip1993]

It sounds like it, have you got any fualt codes coming up