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Q: Rough Idle on 1999 rx lexus 300 on 1999 Lexus RX300

When my 1999 lexus rx 300 comes to a stop, extremely rough idle. Just recently had spark plugs replaced on the car, and the problem still exist. Once you take off, takes a few seconds before you get to your desired speed. There is no check engine warning lights on. After a recent oil change, the hose to the air filter was not reconnected. Several days later is when the problem began. I have been told it is the timing belt, idle air bypass, oxygen sensor, mas sensor among other things. Any suggestions where to start would be greatly appreciated.
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If you had the spark plugs replaced the shop or person that did this work had to remove the intake and if they did not replace the gasket the vehicle should be taking in air and causing the vehicle to have rough idle.I would take it back to the shop and mention this first i would pay another shop to run full diagnosis and find out if the shop where you had this work done is responsible for not advising you that they needed to replace the intake gaskets.
My RX300 was having the same problem. I had the spark plugs and air fuel ratio sensors replace and it fixed it.
As a general rule all that is needed for correcting an idle air control valve problem is cleaning the (smallish) air bypass port/channel. Clean the port/channel/orifice, unplug the battery so the engine ECU is forced to "relearn" the PWM setting for the valve's control solenoid, and be on your way.
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