If your vehicle is showing jerking or surging at steady highway speeds, here are the most likely causes and the parts you'll need to fix each one.
Worn spark plugs or failing ignition coils often cause intermittent misfires that are most noticeable under the light, steady load of highway cruising.
The MAF sensor measures air entering the engine. If it is dirty or failing, it sends erratic data to the computer, causing the air-fuel mixture to fluctuate and the engine to surge.
Unmetered air entering the engine through a cracked hose, intake gasket, or a stuck PCV valve can cause a lean condition, leading to surging at steady throttle.
Degraded transmission fluid or a worn torque converter clutch can cause a vibration or jerking sensation (often feeling like driving over rumble strips) when cruising at highway speeds.
A clogged fuel filter or a weak fuel pump may struggle to maintain consistent fuel pressure at higher speeds, causing the engine to hesitate or surge.
The Exhaust Gas Recirculation (EGR) valve opens during highway cruising to reduce emissions. If it sticks open too far, it dilutes the air-fuel mixture excessively, causing a jerking misfire.
The TPS monitors how far the throttle is open. A worn 'dead spot' right at the typical highway cruising position can cause erratic surging as the computer gets confused about pedal placement.