after warming up vehicle would not idle right when coming to a stop. it was intermittent at first but then got progressively worse. While sitting at a stop light rpms would go up to about 1000 then surge beyond without any input from me and then drop to below 500 sometimes killing the engine at what was suppose to be idle. there were not codes or check engine light but took to dealership when it first started happening they said they couldn’t find anything wrong. during this time i replaced spark plugs, coils and timing sensors trying to fix but it those repairs didn’t take care of it. but then it became more consistent and took it back in and they were able to confirm the problem occurring and after testing they recommended and changed out the timing components and all cam phasers, phaser filters and all vct solenoids