2002 Lexus ES 300 Low Idle, and

So I have a 2003 Lexus ES 300 and it has had a few issues in the past with the Alternator and starter both of which I have replaced. Though, now the car is idling low and has the battery light on even though I replaced the battery with the exact same one that was in the car before as well as having the indicator telling me I have a brake light out even though both are fine. Idling speed is around 250-500rpm. It will run for a while although eventually, the car uses up all of the battery and dies which im assuming is due to the idle speed. Any possible suggestions as to what could be wrong? From researching, it looked like it could be the throttle body or the Idle air control but the car doesn’t seem to be having issues accelerating at all. Any suggestions?

All of these can cause that

Causes

  • Throttle body is coated with carbon deposits
  • Maladjusted throttle stop
  • Vacuum leak(s)
  • Speed/Distance Sensor failure
  • MAP Sensor failure
  • Throttle Position Sensor failure
  • Automatic Idle Speed Motor failure

The battery light indicates a malfunction in the electrical system

Have you had your electrical system checked? I know you said your alternator has been replaced, but I wonder if you killed it trying to charge a depleted old battery before you replaced the battery…It could be an idle issue too, but I would also get your electrical system checked out