Will the car still function if I remove the shift interlock solenoid?

[showme]

I'm working on my grandson's '08 GP and I need some advice. He was starting to have problems shifting out of park and was also having 'reduced power' (limp mode) until it got so bad he called me for help. From what I've learned, the possible culprits for the shifting problem are the brake pedal position sensor, the shift interlock solenoid, and that the accelerator pedal may be one reason for the limp mode. I know the throttle body might cause this too, but I replaced that about 2 years ago with a GM OEM part.

I've put a new brake pedal position sensor on, and a new accelerator pedal/sensor just in case. I have a new scan tool arriving today to calibrate the brake pedal sensor. As of now, after putting those parts in, the car starts, the shifter moves (sometimes), but when I put it in any gear it revs but doesn't kick into gear. I'm hoping this will clear up after I re-set the brake sensor. 

My question is about the shift interlock solenoid. After not finding new ones anywhere, I ordered a used complete shifter with a solenoid on it after asking the seller if the solenoid was for sure good. He said it was, and it's on the way. But if I remove the interlock solenoid from the shifter, would everything still work as normal (aside from the fact that the shifter would no longer need to be in park to complete the start up? Is there anything in the circuit between the brake pedal sensor and the shift interlock solenoid that would keep the car from starting or running correctly? I've already pulled the solenoid but didn't try to start it and check it yet. The car is sitting in the high school parking lot where my grandkids are students. 

 Anyway, the scanner comes in today and the "new" shifter assembly will be here in a few days. I'm wondering if I get the brake sensor calibrated and can get it running and shifting if it would be safe (me driving) to drive back to my house to finish the job. Also, if anyone has any suggestions about troubleshooting the reduced engine power/limp mode, I'd appreciate any help or comments on that. Thanks for any help on this. Lee

Edited Monday at 07:00 PM by showme

[showme]

Update- So the new scanner didn't perform as expected, so i had my mechanic come out and recalibrate the brake pedal position sensor and he told me the car is starting (which it did already), and the shifter is moving into gear but it isn't engaging and he thinks it may be the transmission. I'm not sure how the transmission can cause reduced power, but it makes since that it's causing shifting and gear engaging problems. I just don't want to pay to have the transmission rebuilt and then have it turn out to be something else, i.e., more simple and less expensive. 

  My daughter is a single working mom with 3 teenage kids, one in his first year of college and the other two in high school. I should be finishing up on the grandson's car repair today. (He went off the road and I've replaced his radiator, condensor, fan, low pressure AC hose and a new compressor is coming in today.) Hopefully I'll have it back on the road by this evening. But with my daughter working full time as a nurse, and the 3 kids all in school and working, they are all depending on her Ford Expedition and its' wearing them all out. Any help or ideas on this will be appreciated. 

[55trucker]

Are you absolutely sure that the shifter mechanism on top of the case is properly aligned?

It is an electro/mechanical device that has to properly positioned.

The engine is the 3.8 or 5.3?

The trans IS the 4T65e?

Edited 7 hours ago by 55trucker

[showme]

No i'm not absolutely sure it's alligned. I wasn't aware it needed to be. It's my grandkids car, and I'm an Ironworker, not an auto mechanic. It's a 3.8. No idea what transmission is in it.