High RPM's after start

I have an 02 TB w/63000 miles and this morning i went to start it up and the engine reved up to over 2k rpm and stayed there for thirty seconds or so before falling back to under 1 were it usually is. Then when i start driving the engine sounded like an 18 wheeler shifting gears. After i got up over 65 mph the peoblem stoped until i turned it off for an extended period of time. Then problem started all over again. Just had the transmission serviced and oil changed about a week ago.

If there is an associated decrease in power while these symtems occur, it sounds like the dreaded fan clutch probs others have experienced. RPM at start of 1,200-1,500 or so should be normal, however they should drop within 10 seconds or so. Any DTC associated with this?

There is a decrease in power when this happens it feels like i'm driving a big truck. I don't know what DTC means but there are no codes associated with this problem.

did you find out what is wrong with you truck as i just posted mine is doing the exact same thing 02 trailblazer with 58 000km on it

10 bucks says it is the fan clutch...search the threads for a LOT of in-depth posts on this matter