How many mile are on your Lexus, I work at a toyota dealership, I've seen this code on Corollas, 4runners, and the v6 Tundra, and they were all caused by the MAF, I always check the range with the scanner and find that it's off at 2500 rpm, and it's in range at idle. I will also see the LTFT jump to -38 while accelerating even moderately. Our parts delivery Tundra had that problem and it got extremely good gas mileage, but I imagine the NOx emissions must skyrocket. The part is quite expensive though, but it's easy to install, maybe have it diagnosed and replace it yourself
