2002: Erratic Idle On Start

I have an 02 that upon starting in the morning will rev high, then rev low almost to the point of dying. It will cycle this way for a while then stop somewhere in the middle but still is not idling correctly. My check engine light came on a few weeks ago and I had the guy at Autozone read the codes which was: lean mixture in both left and right side cylinders. His suggestion was to change the fuel filter which I did with no change in performance, and the check engine light is back on.

Any inputs would be appreciated.

Patrick