Engine limp mode

the ECM should have been switched also , you'll have to get the codes and their definitions , something may have gone bad at that time by pure coincidence . Things need to be tested

I changed my throttle body and actually got it to come out of limp mode but it still misfiring like crazy I kept the old ECM in there if that's what's in the breather box I kept it in the car all I did was switch the motors. But I still have a pretty bad misfire it won't go over 4000 RPMs I said service engine soon on the display but no reduced engine power I have a slight exhaust leak that I got to find where it's at in the back of the motor and skipping like you can hear it bad out the tailpipe

And another thing I cannot get it to get over 10.2 volts I'm battery from it won't charge up I don't know if that's from it not running good enough for me to get it charged up by the alternator or if I have another problem with that