I'm, not exactly sure what the code 75 tests, but in the testing process you are suppose to tap the brake pedal. I think there is also a steering test where you move the wheel??? I never heard anyone say it was an issue in a swap. The code 34 EGR I'm guessing momentarily triggers the EGR to open and looks for the mixture ratio to change. I'd think it serves two purposes. One it let the ECU know the electric/vacuum circuit is working and two, it lets the tester know if the EGR might be clogged. Again, I never heard of EGR (other than leaking) being a problem in these swaps. When I removed mine I saw no difference in function though the removal certainly made the looks under the hood improve.
I'd also assume you were not getting a code 11 without the system seeing the coolant temp when the ECU went through its internal check list. My recollection from all my searches at NATO was that a miss (stumble) at idle seems to be very common and often not resolved. Anyway, it is good to see you are moving in the right direction.