MIJeepSL

Hi, I have been dealing with this issue since we replace the 2.8 L engine.
3 things triggers the limp mode:

1. placing the key in accesory position.
2. placing the key in run (without starting the engine) and pressing the brake pedal.
3. when driving without the limp mode on, if I change gear with the shifter (automatic transmission) to second, it goes to limp mode.

if we just turn the vehicle fast, we can run the engine with no problem.
we have ground test the cables we think are common between the brake switch, the ignition key and the transmittion an apparently there is no problem.
what else should I check?