I had a similar problem with my RX350. the driver's DRL would go out and come back on randomly. new bulb same issue. so I wiggled around the wiring and that fixed it. then it went out again. I ended up removing the wiring that went to the headlight bulb from a larger bundle of wires. I guess after 15 years with the hot and cold cycles for whatever reason the loom was pulling too hard on the connector not allowing good contact. freeing it up worked. saved a bunch of $ on a new light or wiring harness. has been fine for the last 2-3 years