My car throttle sudden is hitting high at 1600 rpm from start and continue to go up to 1800. It was at 1500 before and goes down to 1000. Now instead of going down it goes up to 1800 and when the engine gets hot, it goes erratic 1800 down to 1000 repeatedly. As if you are pushing the pedals and withdrawing. What’s seems to be the problem?

 

Check for sticking throttle plate and cable.