I have this problem with my car. I notice when I suddenly floor the car my car will bog and buck like crazy before it starts picking up. It feels like I have hit the brakes when it bogs.

I notice everytime when I shift gears and initially give it a little more gas, the car will start sputtering and bucking. It's a very annoying problem. Say if I were to run through all the gears; after each shift and getting back on the throttle the car would lunge forward and slow down, then pick back up again.

My fuel setup is 450cc injectors, 4:1 fmu, vafc, intank and inline fuel pump. And yes, I have had it dyno tuned. I'm wondering could it be a bad O2 sensor or clogged cat?

 

sounds like it is getting too much fuel.

do you have any way to data log? or do you have anything logged from when you had it tuned?