825i throttle response is off.

I have a 2011 825i with 12000 miles. It was real hard to start and was running on 2 cylinders. we changed the injectors out with ford ranger injectors and now the engine sounds great. The problem I'm having is the throttle is dead if I push it to quick. I can ease into it and it will rev up like it should. If you are cruising and mash it to the floor it goes dead as well.

Any ideas?