engine power

What is your question?

We have had an issue 3 different times within the past 2 weeks where when driving, we get a message saying decreased engine power, and we are then unable to drive faster than 40km..the first two times we stopped, shut the truck off, and when we restarted it, it was back to normal. Yesterday my husband shut if off and it wouldn't start back up right away. Could it be we need a new battery? Or is it something more serious?