My new Regal explained the reason for the decline in engine power.

The engine power drop may be caused by carbon deposit, fuel system failure or air intake system failure. There are many kinds of carbon deposits produced by engines, including cylinder carbon deposits, throttle carbon deposits, spark plug carbon deposits, intake carbon deposits and so on. These faults are all factors that affect the engine power. When there is too much carbon in the engine, the ignition system of the automobile will deviate, the intake efficiency of the engine will decrease, and finally the engine power will decrease, and the automobile may idle.