You indicate that the oven cuts off before reaching 150 degrees. Does the display go blank or does it just cancel the bake cycle? Does the broil function work?
Shut off the house circuit breakers for the oven and
check the bake and broil elements for visible damage. If one of the elements is damaged, it could be causing your problem.
If the elements are okay and the oven works in the broil mode, then you could have a problem with the electronic oven control board. That control board governs the heating of the elements.
If you find the cause of this problem and need parts, you can order them from this page:
Whirlpool Oven Model RBS245PDB8 Repair Parts.
As noted above,
shut off the house circuit breakers for the oven before accessing internal components.
I hope that this information helps. If you need more assistance, reply with additional details.
If you get to the point where you need to have a service technician diagnose and repair this failure, you can schedule service through this link:
Sears Home Services Oven Repair.