Buick Terraza will not go into gear but once the car is restarted it will travel several miles before losing power. Transmission fluid levels appear fine but they do need to be changed. Could this cause the van to lose power though?

What is your question?

2005 Buick Terraza van lost power while driving and then refused to engage into gear. Restarted the van and successfully reversed and drove the van several miles before the van once again lost power. Subsequent restarts enabled the van to travel a few more miles with each restart. Transmission fluid levels seem okay but fluid is old. Could the fluid be worn enough that a sensor in the van causes the van to lose power and prevent driving? If transmission were actually shot, it would no move at all correct? This is very peculiar. Thank you.

How long has your 2005 Buick Terraza had this problem?

Couple of days.