Hi all im having intermittent power drop off when accelerating and vibrations from underside of car when this happens and hearing increased noise from the rear exhaust section could this be a problem with the exhaust manifold or a valve problem mk6 fiesta

Im having the same problem lack if power, had no ecceleration last weekend called aa out gave me a list of codes, said it was a valve and an injecter, its been in the garage all week cost a bomb, drove it this morning still not much power when you put your foot down also sounds like air blowing from somewhere, if I put my foot to the floor when changing gear theses not much there at all, so its back to the garage on monday.

I had a problem very similar to this on a volvo s60. Turned out the intercooler had a crack in it and this was affecting the air mixture entering the engine. It was low on power and was shoving a lot of more soot out the back (was a Diesel). Might be worth asking them to check this? The intermittent problem sounds like it might be something else though.