rx300 dumping fuel bank1 lean and p0125

[strunk]

my rx300 is dumping lots of fuel. codes are bank 1 lean and code p0125. smells rich and no gas mileage.

[Delphius1]

P0125 code is insufficient engine temperature detected to switch to closed loop mode. The ecu has exceeded the wait period for the engine to get warm enough to go closed loop.

So you're effectively running in cold engine mode. Like running with the choke on all the time.

Fix that issue first so the engine management goes into closed loop mode and uses the oxygen sensors to check the mixture. You can't look at the lean running issue until the engine management goes into closed loop mode.

Insufficient engine temp could be a bad or disconnected coolant temperature sensor. Or there could be no coolant getting to the sensor to warm it up. 

A simple OBD2 reader will give a live reading of engine temp. A broken sensor may read low, or get to a certain temp and stop increasing.

You'd have to check to see which it is.