RPM problems in park or neutral

My 98 GTP will only rev up to 4000 RPM while in park. While I drive, it performs fine up to the redline. I don't believe that this is normal. Maybe fuel filter or something on the fuel line? Suggestions are welcome,Thanks.

The PCM will cut fuel delivery, there is no problem, so don't try to fix it.
WHY ARE YOU TRYING TO SPIN AN UNLOADED MOTOR HIGHER THAN THAT ANYWAY?????????????

dont rev that baby to high . you are asking for big trouble if you rev her up while in park or neutral

Thanks BOOZER, I just wanted to find out if that was normal or not. By the way, I was just testing it to make sure the engine was running smoothly. I don't normally do that. :)