I'm new to the forum. My 2000 rx300 is staling at cold start up. It started about two months ago. I've had it in for service a couple of times. First time the throttle boot was cleaned, and it still had the problem. I took it back in, and they couldn't find anything wrong with it. They had me run a fuel system cleaner a couple of times, thinking I might have gotten a bad tank of gas. It still does it. New air filter and PCV valve, also. I hope that covers everything. I have to warm it up for a few minutes in the morning, then it runs fine the rest of the day. I have about 128,000 miles on it, and had the plugs changed around 100,000. Let me know if you have any suggestions. Thanks for your help.

 

I would clean the IAC Valve and see if that helps. Maybe clean the MAF sensor too since it is easy.

 

Just curious,what plugs did you re-install, oem? ex.denso,ngk? As far as a good place to start,Carguy07 has good suggestions.

 

Thanks so much for the help carguy07. I will try that tomorrow. Lexus114, I used NGK plugs. Thanks to both of you for replying.

 

What it sounds like is just an IACV that's gotten dirty, a lot of carbon gets built up inside and a simple cleaning will almost always do the trick. I'll probably try this cleaning again sometime and do a photo DIY for you guys if you're interested.