Air inside engine
You don't.
show me the fuse panel for the 91 ls 400 an witch one is for the alternator
The lack of air intake designed to flow into the motor.
at least 91 octane
Premium, 91 or higher
Use 91 octane or higher octane rating premium gas for the 2009 Lexus RX350
Premiun Unleaded is required with at least a 91 octane rating.
That's what you're supposed to use.
A 1991 Subaru Impreza might overheat because of a leaking cooling system or because of a damaged thermostat. You might also have a damaged or leaking radiator or a cooling fan that is not working.
You should be fine with 91 octane. The higher the octane, the more you engine will like it, but 91 octane is enough for your ES 350.
If your engin light also is on, you need new oxigen sensors!