Hi there
I am new to this forum
When I start my car (when engine is cold) then idle rpm varies from 1000 to 1600 . After 3-4 minutes rpm suddenly increase to above 2000 then decrease to 1500 range after 5-10 second. When the engine is fully warmed up, then rpm stablisie to 700-800 (it has been happening for past 4 days)
One day, when car was not warmed up properly, I shifted the transmission to Drive (from Park) and engine stopped running
The other day, in the evening I visited a mall (parked car for 2 hours) and on my way back home, stopped at a red light, and engine accelerated suddenly, although I had pressed brake pedal.
Any/all suggestions are really appreciated.
Just to let you know, I have been driving this car for past 3 years, and have not done any specific maintenance or repair recently

 

V6 or 4 cylinder?

 

its a V4

 

The engine is either a inline 4 cylinder or a V6.

Assume it is a inline 4 cylinder model number 5SFE

Idle speed is controlled by the Intake Air Control (IAC) valve. This valve can become dirty and stick. An internet search on cleaning the IAC valve for the model engine should result in many hits. You can read up on the this.

Might also be the coolant temperature sensor for the engine computer. This can result in the computer receiving false info on the engines coolant temperature.

The Autozone website at www.autozone.com might have info on testing this sensor in their self help vehicle repair section. You will need to obtain a free Password and User ID to use this site but well worth it.