Just curious I was checking my 03 GMC Envoy idle after tuneup and noticed that when reving the engine from idle in park it struggled to get up to 3000 rpm. I checked online and found out that there is a rev limiter on these engines (4.2 l) and not to worry that this is normal.
As you heard and like @FlyingFischer said it is normal on these trucks. It can be tuned out so you have no limit. @limequat is our less expensive tuner on the site and does a great job. If you'd like to get it done he can also bring new life to your truck via a tune. It really puts some pep in it.
If you really wanted to get past the rev limiter without a tune (do so at your own risk obviously) is to move the shifter so its in the middle of Park and Reverse. You know you did this right when the square box that is on the selected gear in PRND "disappears" and should be able to freely rev the engine past the rev limiter. Of course, the risk is apparent if you tried putting it back into park/gear while freely revving the engine will tear up the tranny before the idle settles back down.