My Hyundai Sonata keeps high revving on the rev counter,It

My Hyundai Sonata keeps high revving on the rev counter,It jumps back down when you stop/start engine?
Whats wrong and today stopped four times but wouldnt jump back down its a seven yr old 2.5 six V engine.Automatic

Car jumps when you start up then drive up to four on the rev counter then on occasion jumps again and drives usually.

Throttle position sensor can be going out it causes the engine to rev when you're sitting still for no reason. I had it happen on my mother's accent. you'll want to replace the part or take it to a mechanic that is familiar with the Hyundai since they seem to be picky about who touches them.

I had a alike problem with my 2.0 litre Daewoo Nubira they most likely use the same parts and engine management systems. Tried some ideas from mechanics to no avail, what cured it disconnected the battery for a couple of minutes to reset the computer Job done, be sure you have the relevant radio & central locking codes to hand, as they'll need resetting also Good Luck