I just fixed my 99 RX300 for the same problems and symptoms for bank 1 (close to the firewall). The codes were p1349 Variable Valve Timing (VVT) System Malfunction code and misfire codes p0300, p0301, p0303 an p0305. Rough idles, hard brake pedal at time, lurching and also engine/transmission humming at steady 80kph experienced. Found alot of info on OCV replacement from Google but no specific causes to valve failure.
I check the ocv filter ok, check OCV resistance ok (compare B1 to B2). Check OCV B1 mechanically by shaking the valve and compare to b2 and notice the shuttle valve moves more easily (louder noise when shaking indication of the OCV fails mechanically). Replace B1 OCV, clear DTC and been driving for more than 100 kms and CEL has not come back yet. Before replacement CEL turned on after drvining for approx 15 kms on first drive cycle.
Good luck.