I have a 6 cylinder, 2003 Trailblazer EXT with 85,094 miles. I just recently started experiencing a problem. I have noticed that when I reach 30 mph the truck stays revved up and doesn't go back down as long as I am above 30. When it goes below 30 it slowly decreases. Your suggestions and comments are greatly appreciated.

Welcome to AF, dirty throttle body, throttle control motor not working properly, tps skewed, a full scan would be appropriate if cleaning the throttle body is ineffective.