My 1995 sc300 Shut off during idle, when I start up the car the RPM right about 1500 then it drop down to 1000 and keep going down to 0 that time it shut down.
I tired to clean IAC valve, put it back together it didn't drop down this time but it unstable, RPM neddle going up and down make the engine shake so bad.

Please help

 

Did you take the throttle body off to clean IACV. If you did, check all vacuum hoses. Did coolant run into the spark plug alley. Did you fool with the TPS, when I remove my TPS I get similar idling. Give little more info of what you did before this started.

 

...also don't feel bad when they move this thread to appropriate forum.

 

If the RPM is going up and down at idle it's usually a sign of a bad or uncalibrated TPS sensor.

 

Clean Throttle body, could be carbon buildup. Check for vacuum leaks.

 

After I took off the IAC valve to clean, then put it back. It's go up to 2000 RPM then it's stay there not go up or down.
It only stay on 2000 rpm when idle in park gear or neutral gear, if I go for reverse gear or drive it will drop down to 1000 RPM.

 

Before you reinstalled the IACV did you screw the plunger back all the way in?

 

yes, i did put it back in correctly.

Do you think it's could be Oxygen sensor or the coolant sensor?