2001 Nissan Maxima hesitation during hard acceleration

The same problem occures during normal acceleration, but is more evident during hard acceleration. After reaching approximately 3000 RPM the rate of acceleration slows segnificantly. The car continues to pick up speed and RPM continue to go up, but at a much slower rate until the upshift. The simptom is very close to that of a manual transmition that starts to slip, exept the car has AUTOMATIC tranny. I'm just using manual transmition as an example to better descripe the problem. CEL is not on. Idle is fine an otherwise the car performs as normal.