1995 M/T, dp, catback, stock ecu

I am not referring to the 3k hesitation on acceleration.

I mean, I am in neutral and I rev up to 2.5k and let off the throttle...

Rather than a smooth drop down to idle, it seems to 'stumble', like drop down to 1.8 for half a split second, then 1.5, then 1.3 then to idle. This happens fast, but it is noticeable as the revs dont fall smoothly.

Is this normal behavior? It's been this way since I had it and runs great in other respects.