"Lunging" under throttle

[Mudfrog]

I'm having an issue with my 02 Tahoe 5.3 Flex. Under throttle, typically above 2k you feel it more, it feels as if the Tahoe is lunging forward for a split second. With my louder exhaust it also sounds like the rpm's drop but I do not notice it on my tach, but you can feel the Tahoe actually speed up for a split second then slow down for a split second. The problem is amplified when I have the AC on, not sure if that helps any.

I've replaced the plugs, wires, MAP sensor and fuel filter. I've also cleaned the MAF sensor.

Anyone have any other ideas of what it could be? I'd prefer not to take it to a shop but if I need to I will.

Edit: Forgot to add that I have no check engine lights.

 

[Rivieraracing]

I'd be looking at fuel pump, start by getting the fuel pressure checked

 

[Mudfrog]

I'm dropping it off at a shop today. They are going to check the fuel pressure and hook it up to a scanner.