Lack of power

I have had injector seals changed twice new fuel pump fuel filter and pressure valve changed because of the car cutting out, this has cured this but now no power, flat as a heghog crossing the M1.
If I disconnect the Mass air flow sensor power returns but gear changing (auto gearbox) no good dwells too long sometime
Any help

Not an expert on MAF or Autos, but I'd suggest replacing the MAF, set it up using a Nanocom or similar and clearing faults, do a basic service, filters etc, then when it's running right sort the autobox issue which might have been set to kickdown at a lower power to suit the nackered MAF.

Someone else more knowledgeable might shoot me down later, but I don't care ..

Tester is needed