won't go past 3500 rpm

[scruffy1]

I was sitting in the driveway and noticed the engine miss a little when the a/c was on. Tried to rev the engine to see if it would even out and it would not go past 3500 rpm. Same with a/c off. Otherwise runs fine.
Don't know if this is related but I have been having the PO401 blues. Changed all components but still pulls the code!
Any help appreciated for this newbie.

 

[Jspafford]

If you have an auto and it was in park or neutral there is a rev limiter that keeps it from revving up while not being in a driving gear.

It is perfectly normal.

 

[scruffy1]

Whew! Thanks. I just bought this truck and the P0401 thing is driving me crazy. Was going to be very disappointed if the RPM thing was another problem. I'll repost my EGR issues in a new thread.