Power loss at 3K rpm, no cruise

2001 GMC Sierra, 8.1L, 50K miles.

Today my cruise control stopped working. I made sure it was turned on, pushed the button, nothing.
Then.....after the truck sat for about an hour I drove it to town. When rpm gets to about 3000, it loses power like it was shut off. Once rpm gets back to about 2000, it takes off again and will drive fine until rpm get to 3000 again.
Then.....on the way home from town, I noticed the shift indicator is not working except only when it is in Park.

All these things happened just today with no warning and no check engine light. This is the first ever problem I've had with this truck.

Does anyone have a clue what is going on?

Thanks for any help or suggestion.
ra

Change the fuel filter, it makes all kinds of other stuff react weird if the fuel pressure keeps fluctuating and falling off.