Keeps over revving and accelerating by itself?

Hello,

There are few possibility of why this is happening.
Does this over-rev when you are in neutral?

This can be due to a weak idle air control valve (IAC). If the IAC has a weak spring it can allow more than usual amount of air through and cause the engine to rev higher than it would have other wise.

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

Another possibility is that you will have to adjust the throttle cable. It could have came off the bracket or got loose. So check the cable and make sure it is secured. You can also adjust the cable as well. I have attached adjustment procedures.

Please let me know of any questions.

Thank you.