Lately the RX 300 has been surging while braking during routine stops. The car will surge while braking and once I come to a stop it completly dies at the stoplight. It helps if I keep rolling but that only goes so far. The car rpm's go up and down between 10-zero mph. Not sure if this is a faulty Idle air control sensor? any suggestions / fixes would be appreciated.

Thanks!

 

My knee jerk reactionary response would have been "vacuum" or loss of it.

But I would suggest getting a obd dump.

Salim

 

I had this happen not too long ago a few blocks from the gates of my track and sure enough the rpms got high really quick and then went down and the vehicle shut off. I checked the OBD2 code and it was a P0171, which Salim alluded to in describing it as vacuum.

A few other times it sits high at the light and it won't stall.

Both times afterwards I cleaned off the MAF, the IACV along with resetting the battery and no such problems, though occasionally I get a low idle, and in that case I cleaned the IACV valve again. Another trick I used as of late is to tightened the accessory belts as shown by TunedRX300, https://www.clublexus.com/forums/sho...d.php?t=272697 and that appears to have kept the rpms steady ever since.