I think I experienced what you describe and I think it is the transmission, not the engine. Happened to me a few times when driving slowly, wanting to change the lane while accelerating hard (to get in front of a car that is approaching). When I floor the accelerator I feel like instead of dropping to the right gear and going forward, the car is dropping gear by gear until it gets to the right one, but the process takes what feels like eternity, but is probably around 1-2 seconds. However, when the car on the lane I am trying to jump into is approaching, that is not very fun and definitely not expected. During the process of hunting for the right gear the car almost feels like it is coasting, before the hit of strong, but way too late, acceleration.
I think that is the downside of an 8 speed transmission and fuel economy. It goes to the highest gear very quickly, and is reluctant to downshift. There have been times when I floored the accelerator, but due to the time it took for my car to actually start accelerating I ended up pressing the brake pedal and staying in my lane. All the transmission did was shift to a much lower gear, but due to the time it took it was useless. Most apparent when driving slowly, 15-25 mph and trying to change lane while accelerating.