cx7 jerking on acceleration

[brooklyncx7]

I have a 2007 mazda cx7. Ever since a timing chain and vvt repair. My car has intense jerk when accelerating. It feels like its not getting enough gas or someone is tapping the breaks. After driving for about 25-50 miles the jerking would go completely away and the car drove perfectly fine. At first i had a "too lean" code. Replaced some hoses and ran a smoke test-problem remained. Also updated the ecu. Then got a code for an oxygen sensor. Replaced it and the car drove fine for about 50 miles.
Then after driving the car like that for a few weeks (jerking that would go away after a while) the car drove completely perfectly as soon as a cel came on. The cel that came on was no activity in oxygen sensor. So no oxygen sensor it ran fine. So then i decided to change the o2 sensor again but this time with the genuine mazda sensor.(had a bosche one before) Once again once i changed it the car drove perfectly fine. As soon as my gas went below half full the jerking came back! Thats the point im up to now. Currently the jerking isnt as intense as before. If i slowly accelerate there is almost no jerking at all. As soon as I accelerate hard or floor it it struggles getting up to speed and starts doing a swaying jerking motion until it breaks through and blasts off.
Any ideas? What could cause this? Could the ecu be relearning the new 02 sensor and should I just give it time? Any input appreciated thank you!