2000 chevy blazer rpm surging between 1000-1500 while going up incline it stops above 1500

What is your question?

It happens on excelleration on an incline started a week ago and seems to be getting worse. It stops after 2000 rpm’s. No problem with cruise control at around 1700. I did a fuel pressure test the fuel pump tested good the fuel filter was replaced around 5000 miles back I just checked for vacum leak seems good. I didn’t use any test equipment just a physical check

What makes this problem better or worse?

When I give it more gas and raise the rpm’s it seems to run fine

How long has your 2000 Chevrolet Blazer had this problem?

1 week