GM can flash the ECM to a GM tune like mentioned. Only thought is if the ECM were damaged somehow that it may not finish. Just requires additional steps like mentioned I believe. Part of the way their system works. No need to remove the switch. It will not be in use since the GM tuning does not look at those pins. Basically inert to the system. Also sounds like normal operation of a DSP5 switch. Just have to use a Flashscan V2 or Autocal to confirm the switch is selecting the base and the 4 DSP positions correctly. Some switches are six position and an index plate is used. If the index plate is in the wrong position then the swithc may only see 4 different positions and 2 of the 5 would probably be the same.

if overheating I suggest removing the fan shroud and clean the radiator and intercooler really well. I have seen post on other forums where debris has blocked the air tunnel. Last thing is check the fan to see if it is locking up when up to temperature. It is mechanically heat control to lock when it is hot enough.

Brian