2012 Mustang GT500 5.4 swap to 5.0

Few questions here, have a buddy who has a 2012 5.4 and blew it up took to a garage and they talked him into putting in a 5.0. My question is the pcm for the car is not with it no longer so I purchased the correct one to the vin but its for a 5.4 and not the 5.0. Tried to start it up and no start just dumps fuel. I changed the software with IDS to a 5.0 and now it starts but have issues with no throttle and idles high then dies.What do i need to change in hp or can some one guide me in the correct direction. Newbie here

You need a custom tune - you have to be more specific on parts used as this is probably a mix of two parts bin

Ya for sure you need more info for your calibration did you write the stock vin from the gt500 with ids or the 5.0 vin and calibration? If you used the gt500 vin the calibration will be set up for a 5.4 not a 5.0 no matter what Copperhead PCM you bought. Let us know what all was done and be specific. What fuel system is being used we need all the details to try and help you also post the ids read from you MPVI.