As jwmelvin mentions, the NSX (and just about all OEM ECUs) do fuel cut when the throttle is lifted. There are usually some software limiters that will prevent fuel cut such as: MAP must be less than x, throttle switch less than x, RPM less than x. These settings attempt to confirm that you are de accelerating and attempt to make the fuel cut - fuel restore transition smooth when you have lifted the throttle and are de accelerating. If you have an OEM ECU these settings are non adjustable. If the MAP input and RPM inputs were messing up, you would likely be generating error codes or have other issues. However, if your throttle switch is slightly out of adjustment or the throttle switch is worn in the low opening area this could be causing a problem with smooth transitions at low throttle opening without generating a TPS error code. Typically, the software might block fuel cut when the TPS is less than 5% open. If your TPS is worn (think worn stereo volume control that goes high all of a sudden at a low setting) or the TPS is out of adjustment, you could be getting the TPS on - off transition at a bad point causing the engine to cut - restore - cut - restore fuel. The NSX has a fair amount of lash in its drive train which is quite noticeable in the lower gears and problems with transitioning in the fuel cut will really amplify this.
You didn't identify whether your car is cable or DBW throttle. If you have a cable throttle, make sure that the cable is operating smoothly and not causing the throttle to hang up.
You mention that the wobble occurs on static throttle at 2000 RPM? Does that mean throttle closed, car in gear and de accelerating? If so, at 2000 RPM the ECU should be in fuel cut mode. However, if the TPS is out of adjustment or worn, the TPS signal might be transitioning between cut and restore levels causing the 'wobble'.
If you have access to an ohmeter, it should be relatively easy to check for smooth operation of the TPS without taking it off the car (it is just a simple rheostat). I also seem to recall seeing a procedure in the shop manual for setting or at least checking the settings on the TPS. Finally, the TPS is usually a dumb-ass reliable device so diagnose first. Replace the switch or do the adjustment only if checking confirms that it is out of adjustment or has a worn spot. Unnecessary replacement or adjustment on a functioning switch offers the potential to mess things up.
