my 96 Honda accord starts to rev up and down on its own after I have been driving awhile. does anyone know what my problem might be or how I can find out? any information on that and how I can fix the problem would be great. thank you.

 

Could be a number of different things. However, where it only happens after it is warm. That points more toward the engine coolant sensor or more than likely something with the fast idle thermal valve.

Is your check engine light on?

How is your engine coolant level?

What RPMs does it bounce between?

Does it only happen when the car is in drive and does it stop when you put it in neutral?

Another thing to look at would be the Intake Air Control (IAC) valve not operating properly