For example, when the rpm reached 2200 at 100km/h on flat road the car is all right, until there's uphill and the rpm shows sudden drop up to 1400 and gets jerk and shuddered like misfiring symptoms. Then I have to accelerate more, up to 2700 - 2900 rpm to ensure the car is not jerking on uphill state. But I noticed even at 2800 rpm, the car seem heavy to move like something is blocked/stucked on the firing system.
