Bad Spark Plugs

• Spark plugs are responsible for igniting a vehicle's air/fuel mixture, a process that creates engine power. Bad spark plugs can negatively impact ignition of a vehicle's air/fuel mixture, which can cause engine hesitation, missing and knocking, either during acceleration or under constant speed.
  
  

Bad Spark Plug Wires

• Bad spark plug wires can negatively impact the flow of current (electricity) to the engine's spark plugs, which can result in incomplete spark plug firing and engine combustion, which can both lead to engine hesitation during acceleration.
  
  

Dirty Fuel Injectors

• Dirty fuel injectors impede the flow of fuel into a vehicle's engine cylinders, and this can cause restricted and/or incomplete engine combustion, which can lead to both engine hesitation and the engine missing during acceleration or at cruising speeds.
  
  

Bad Carburetor

• On vehicles equipped with carburetors, engine hesitation can be directly caused by a bad or abnormally functioning carburetor. A carburetor is responsible for injecting both air and gas into a vehicle's engine cylinders, and if a carburetor restricts the flow of either one, engine hesitation can occur, either during acceleration or at cruising speeds.
  
  

Dirty Fuel Filter

• Fuel entering a vehicle's engine has to first pass through the fuel filter. A dirty, obstructed fuel filter can restrict fuel flow into a vehicle's engine, a condition that can cause engine hesitation during acceleration.