I have a 2002 RX 300 with 114k miles. Over the course of the last few days, I have experienced an extremely rough idle when first starting the car. It actually died one time when I put it in drive. Once the car warms up, it seems to get better. What could cause this? Idle air control valve? Timing belt? Clogged or stuck fuel injector? Air/ fuel sensor? The MIL is not on and I hooked a code reader up to it and got no codes. MIL is ok, as is the fuel system indicators and O2 sensor indicators. Thanks

 

IAC valve can cause this.

 

x2, clean the IAC. There is a diy in the sticky for this.

 

This morning the car would not start without giving it gas. Ambient temp was 55 degrees. It would not idle at all. After 4 or 5 minutes of keeping the RPM's around 1500, the engine warmed up and idled fine. Is this definately a faulty idle air control valve issue? Anything else to consider?

 

It is more than likely the IAC. All your symptoms point to that.

 

MAF sensor needs cleaning and also run some fuel injector cleaner in your gas, though the IACV needing cleaning is the first likely culprit, the other two have an effect on idle also.

 

IAC nad MAF sensor. For sure.

 

Thanks guys. Cleaned the IACV this morning and the car idles fine now, even when cold.