Need help! - Engine "hiccup" at ~2800 RPM? (Video inside)

Having a problem with my 91 Comanche Pioneer. 4.0 HO, 4x4, AX-15. When the RPM is sitting just below 3,000 RPM there is a "hiccup" that occurs randomly, but somewhat predictably. I've only been able to replicate it in 3rd and 4th gears, but it may happen with others. It does not happen at all when the RPMs are 2,600 or below, or above 3,000. Just in this one tiny range. Here is the video I took (sorry for the loud road noise.... cold air intake has gotta go)

https://www.youtube.com/watch?v=k8p-2I1OxaI&feature=youtu.be

My buddy who knows a lot about these Jeeps had no idea what it was. Thought it might possibly be something with the distributor, or a sensor somewhere.

Any ideas?

Have you checked for fault codes yet?

https://comancheclub.com/forums/topic/54009-need-help-engine-hiccup-at-~2800-rpm-video-inside/?tab=comments#comment-550523