Did u change fuel pump as different btwn mfi and efi.That prob why losing power at higher revs. Also check your timing is spot on, plugs are gapped correctly,throttle position sensor clicks when you 1st press on the accelerator. Once these are all checked,check for air leaks on all the boost hoses and make sure you have no air leak anywhere else.
Then you can start checking faulty parts. - but im 99% sure its one of the above or a combination of all. Where did u get it tuned? Was it someone reputable?