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Q: idle control valve and shifting problem on 1999 Lexus RX300

i have a shifting issue from 2nd to 3rd gear, and from stop to 1st, it jumps a little. took it to transmission guy who said my control valve needs fixing, but another guy says control valve has nothing to do with transmission... ? he said he could reset my computer but another guy said i have to take it to the dealer only for a control valve and reset..... any advice?
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The RX300 do experience problems with the idle speed control valve (IAC). It is located at the bottom of the throttle housing. My experience is the dealers replace them, but many independent repair shops that specialize in Lexus or Toyota will remove the air induction boot and clean the idle air control valve. Carbon builds up on it, the barrel that should rotate inside the IAC binds causing the vehicle to stall particularly when the car is started from cold. I have cleaned many of them with no come backs at all.
Call someone that specializes in Lexus /Toyota ask them if they have seen this problem and do they clean or replace the IAC valve.
The IAC valve should not effect trans shift from 2nd to 3rd gear. If you experience stalling from a cold start or low idle speed or stalling when the headlights, air conditioning and or steering is cranked fully to one side, address the IAC problem first. If no stalling is experienced, when was your transmission last serviced? Have a trusted shop drive the vehicle, get the trans oil hot, drain the trans oil, remove the trans oil pan, replace the trans filter, drain the transaxle differential and refill the transaxle with genuine Toyota fluid. For extra assurance I like the transmission oil additive "Lubegaurd" it is the only trans oil additive I have ever used that I have seen work. Hope this helps, tell your friends about "Repairpal".
Do you suggest having the IAC cleaned or replaced? If a cleaning is only needed; how often does this problem occur?
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