If your vehicle is showing engine surges or accelerates without pressing the gas, here are the most likely causes and the parts you'll need to fix each one.
An improperly secured or stacked floor mat can slide forward and physically press against or trap the accelerator pedal, causing unintended acceleration.
Unmetered air entering the engine through cracked hoses or failing gaskets causes the engine computer to add more fuel to compensate, leading to a surging or high idle.
The IAC valve regulates the engine's idle speed. If it becomes clogged with carbon or fails electronically, it can stick open and cause the engine to surge or idle excessively high.
A failing TPS sends incorrect pedal position data to the computer, or a carbon-fouled throttle body physically sticks open, causing the engine to rev unexpectedly.
A dirty or failing MAF sensor miscalculates the amount of air entering the engine. This leads to erratic fuel delivery, which can cause the engine to surge or hesitate.
A PCV valve that is stuck open acts like a large vacuum leak, drawing excess air and crankcase gases into the intake manifold and causing the engine RPMs to surge.
In modern 'drive-by-wire' vehicles without a physical throttle cable, a failing electronic pedal sensor can send erroneous acceleration signals to the engine control module.