nickleinonen said:mine does the same thing... 300 rpm isn't much to worry about... but when i am coming to a stop, i don't go into neutral until i am at about 1000rpm in 3rd gear, then pop into neutral and coast/stop.
it is the nature of the engines electrical programing. it isn't fueling much [if any] when the engine rpm is coming down and has to start fueling to main idle speed... also, the ecm does not know if you have it in gear or not without doing this. . it won't do it at a stand still since there is no vehicle movement. . while moving it is trying to make sure it is in gear... my 03 gasser with 5 speed manual did a very similar thing.
it is normal... don't get so worked up over it...
hard for the truck to take off when in neutral or clutch pushed in... and it won't surge when in gear...
***edit***
i guess i should read all the posts before posting, as i wrote nearly the same thing macdaddy wrote...
I was in the local mall parking lot. I waited for a woman to back out ( I was being nice to let her out, I was not parking, just passing by). I put it in first gear while waiting. when she pulled away I started to pull forward. I just let the clutch out no throttle (slight down hill). The truck started to move but slowly because of first gear. I lightly accerated, lifted, clutched, put it second, let out the clutch ( no throttle) the truck rev's up and takes off ( my foot is flat on the floor). I am taken by surpise and put in the clutch and slam the brakes. I looked down as it was coming to a stop the tach is swinging down past 1500 rpms!!!

P. S. I drive for a living, so no it's not operater error. I thought maybe on the first time but when it happen again I knew there was a problem. Thanks guys