If your vehicle is showing hesitation, stumbling, or hiccups when trying to accelerate quickly, here are the most likely causes and the parts you'll need to fix each one.
Spark plugs wear out over time, increasing the gap between electrodes. Under hard acceleration, higher cylinder pressure makes it harder for the spark to jump this gap, causing a misfire or stumble.
Ignition coils break down internally over time. They may work fine at idle or light cruising but fail to provide a strong enough spark under heavy engine load, leading to hesitation and misfires.
The MAF sensor measures air entering the engine. If dirty, it underestimates the sudden rush of air during hard acceleration, causing the engine computer to provide too little fuel (a lean stumble).
Hard acceleration requires a sudden, high-volume surge of fuel. A clogged filter or a weak fuel pump won't be able to deliver enough volume under demand, causing the engine to starve and hesitate.
Leaks in the intake system allow unmetered air into the engine, leaning out the air-fuel mixture. This is especially noticeable as a hiccup or stumble when first snapping the throttle open.
The TPS tells the computer how fast you are pressing the gas pedal. Dead spots in the sensor or heavy carbon buildup in the throttle body can delay the fuel enrichment needed for sudden acceleration.
A melted or clogged catalytic converter chokes the engine's exhaust flow. The engine cannot breathe out fast enough during high-RPM acceleration, causing a severe loss of power and hesitation.