Anyone ever heard of a pronounced yo-yo at 5000-5500 rpms at part throttle?

I'd sure appreciate any suggestions.

I posted this earlier, but perhaps all the detail at the beginning made it hard to read.

So I edited it out and reposted here.

The details are below:

It happens at part/half throttle. TPS (Throttle Position Sensor) between 43-48, especially noticeable in 4th or 5th gear, but also 3rd. I use a ScanGauge II, so I can see the TPS, Intake Air Temp, Manifold Air Pressure in lbs./sq. in., Ignition Advance, Water Temp, RPMs, Battery Voltage, etc.

It seems that the only repeatable trigger is the constant TPS between 43-48, typically in 3rd-6th gears. Also seems to begin about 5000 rpms, in 3rd, 4th, subsiding around 5500, but in 5th or 6th, it'll start at 5000, and continue up to almost 6000 rpms.

The car's typical whine when accelerating (Alta CAI) is interrrupted by a quick on-of on-off cycling action. As long as the throttle position stays relatively constant between 43-48 TPS it'll exhibit this lack of smooth acceleration until I hit 5500-6000 rpms.

It's as if the car is leaving and then re-entering a closed correction loop or something. I estimate it happens about twice/second. It's a funny whine/no whine sound, while the car pulls and hesitates in synch with the sound.

At one time I suspected the belt slipping, but that was before inspecting it and noticing the definite spot where this "yo-yo" occurs.

If I apply stronger throttle, or full throttle (TPS 88), it won't do it.

Easier to notice in higher gear, such as 4th and above. Trouble is, when testing it, by this time, the speed is, ummm, a bit higher than I might use for highway driving...

I wondered if it might be the recent retune of my Unichip to address the afr in colder weather. But when I switched to the older map, it still exhibited the same problem.

Re the engine, I have insulated Alta CAI w/boxtop, 15% pulley, 2% crank, m7 DFIC, m7 400 cc injectors, m7 intake runners, m7/Cosworth head, Schrick cam, NGK one range colder (did have two ranges colder, but had some "random misfire" codes in colder weather, eliminated with going back to the one range colder NGK), latest Unichip.

OEM header/cat, but ceramic coated. Milltek exhaust.

Re gearing, this is an 06. I also use lightweight 15" wheels with 205/50-15 tires for street use.

All these have been on the car since I bought it new, back in the summer. Installed at the 1250 break-in point.

When I auto-x, or play in the twisties in the GA mountains, it's usually OK, because they aren't generally part (half?) throttle applications. But you'd be surprised how often this happens on the interstate. I'll just step on it a bit to pass without downshifting, the car steps out nicely, and then, yo-yo-yo-yo...

All that being said this car is strong and pulls authoritatively (SpiderX and Gr8Force have commented to this effect from their firsthand experience).

Car pulls smoothly and strongly through the dreaded 3000-3500 rpms range (although it took several Unichip tunes & tweaks to get it just right last summer).

Just as long as I don't let it drop into that yo-yo twilight zone...

Help!