I have pretty much the same problem as well, but for me it doesn't happen 100% of the time. Also, it just started happening a couple of weeks ago.

What happens is that when I depress the throttle the engine just lags. If I keep depressing it all the more the engine then kicks in with nice power. Also, when I just mash on the throttle it will also kick in with nice power.

I have a A/F gauge hooked up, and I've observed that when I have this problem the O2 sensor doesn't oscillate like it normally does.

I'm wondering if I might have a bad O2 sensor, or if another sensor/system could be causing this? I'll have to troubleshoot it more, for sure. I just would like to know what would cause the O2 sensor to stop sending out an oscillating voltage?