Mine has the same surges and drops in RPM that are being described. It's done it once within a minute of my Jeep starting (low speed in parking lot), but usually it's after it's been driven a bit, and it does it more with AC running. It'll do it (so far) a maximum of 5 times in a row. It'll surge and drop a couple times, and you can feel it/hear it through the vehicle. Very noticeable. Happens when driving sometimes, the RPM will surge up, and you will feel it a little bit, and when i am nearing full stop, or idling at a light.
So far I have only cleaned throttle body, changed air filter, run gas treatments, and downstream O2.