Ok... Here Goes....

Does it spit and sputter? NO (Idle tubes have been drilled out to .032" also)
Does the tail pipe whistle? NO
What gear are you in? ALL GEARS (AX-15)
Which engine? 4.2L I6 W/CARTER BBD CARB with about 135K Total miles (Stock California Motor (was rebuilt/reman by PO about 1500 miles ago)
What gears and tires are on the thing? Stock 3.07 GEARS w/ 31 x 10.5 Tires
Will it make more rpm in LOW gear? If you mean in low range, I don't think so, But I haven't tried it yet.

It acts like it's hitting a rev limiter or something. It seems to rev fine up to 3K, but then won't go any higher.

(I just thought of this..What if the problem is the linkage not opening far enough? I should get SWMBO to watch the tach while I rev it from under the hood.)

Thanks for your help!
Ed