First of all, go check your fuel cap whether tighten properly. It's torque lock cap, you can close very tightly until the torque lock start to click to ensure no leakage.
Secondly, it's a blardy fuel injection car. You wouldn't know when the injectors clogged up and spray fuel abnormally. Especially those who always stuck in jam. Bear in mind, clog up does not mean no fuel go in. It could be nozzle jammed and fuel keep dripping. Other than that, mixture of air fuel also greatly depending on the fuel injector to spray mist, so it can easily mix with air. Complete burning begun with good air fuel mixture, so that could be the case.
Anyway, the above are plain speculation. I recommend you to take your car to a safe place, tarik 1~2~3 redline pull. If you do not know what does "PULL" means,
Gradual accelerate to 2krpm on 1st gear. Maintain for a few seconds on the same RPM. Then you go pedal to metal until red zone then you either upshift or brake to slow down. Back to normal driving.
Whilst driving on 2nd gear at 2krpm, maintain the same speed same RPM for awhile. Then you go pedal to metal until red zone. You either upshift or brake to slow down. Back to normal driving.
Whilst driving on 3rd gear at 2krpm, maintain the same speed same RPM for awhile. Then you go pedal to metal until red zone. You either upshift or brake to slow down. Back to normal driving.
I don't create these sohighness method. It's my previous magician from kampong told me petrol dirty or makcik driving style or too much traf*** jam can cause injector nozzle jam. Reason to maintain 2krpm is to make the injector get used to that 2krpm spraying rate. Sudden acceleration to push more fuel through the nozzle so it clear up whatever that is jammed in between. 1st gear you can reach redline very quickly, 2nd gear you reach redline slightly longer, then 3rd gear you'll take even longer time to reach redline from 2krpm. So you give the injector a complete training. If you dare enough and or traffic condition allowed, 4th gear pull also can do. However, top gear pull is not recommended unless you have long enough straight road like in the Utah Sald Lake. By right if normal injector jam, 3 hard pulls can clear it up and your car should be back to normal liao. Probably feel more powderful after the pulls.

Yeah as u said i almost every weekday when back home also caught in heavy traffic jam ~ ... so i shall try you pull method when i free, Thank you very much