What make my car to stop.. when driving it just on 2006 Pontiac Grand Prix

been told to change tranmission +SHIF GEAR 3,4 and it steal does that .. did put on a computer to get a code but every time that the car shots seem that it resest it self so having a big problem to get a diagnostic... very dangerrous on hyway..

Asked by for the 2006 Pontiac Grand Prix
scan codes and post so we can adv. post eng and trans codes if possible
2 more answers , 1 more comment
"very dangerous on highway"---depending on priorities--like LIFE---maybe getting it to a local shop(get references) and having it driven and diagnosed first hand might be a good idea.
What did your car shoot the code down? It is dangerrous to steal your shifting. Don't change your transmission yet. Reset itself is a big problem for diagnostic.
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