Again, try rotating the maf 90 degrees. Also, like karthief says, ecu may need clearing. After that it may need a little time to learn the new injector setup before things work like they should.
plugs cause the higher RPM sputter? Could be, it depends on how the air flows inside the tubeTo avoid having the wiring harness to the MAF stretched do you think the 9 o’clock position will be the same? Guess it’s a free trial and error