My dad's Camry has this strange issue under slow acceleration that we haven't been able to resolve.

The car is a regular 2019 2.5L Se, has 61000 miles.

For example, when slowly accelerating on a highway at around 2500 rpm to 3500 rpm the car starts noticeably shaking, jerking and the rpm indicator stats jumping up and down while the car is doing that.

If you give more gas the car seems to "snap out of it" and keeps accelerating as it should. If you let off the car stops jerking too. If you're able to keep the car in this rpm range (presumably at higher speed) the car keeps jerking indefinitely.

This issue doesn't happen if you step on gas hard, downshifting and going straight over 3500 rpm.

Here are the things we did to diagnose and fix the issue.

Ran the diagnostics with Techstream and it's clean no codes come up. First we changed the spark plugs and had transmission fluid changed. There are still no codes but the acceleration issue persists.

Then we had a mechanic look at live data on a scan tool while replicating the issue. He said that transmission displaying no abnormalities and only thing he could see was that the variable valve timing was showing low oil pressure while the car was jerking.

So he refers us to an engine mechanic. The engine guy first disconnects VVT exhaust adjuster magnet (Part Number: 15370-F0020) and has us run check the issue again in order to be sure that it's not a transmission or some other issue. We try to simulate the problem again but the car doesn't jerk or shake this time. We replaced the VVT magnet part but the problem keeps happening.

Next we open the engine and replace the timing chain, VVT exhaust sprocket (13070-F0020), chain actuator, VVT solenoid (1525025010) and camshaft bolt (135A0-F0010).

But the issue is still there. What do we do in this situation?