Yes, throttle body injection is what I tried on the chevota. It was somewhere between the carb cleaner inj and a carb. It's supposed to be a great setup, but it didn't like me n I didn't like it.
If you're not running too rich for the O2 sensor, then you're not making full power. The sensor tries to make the mix ideal for emissions which are too lean for max power, and from what I've heard, too rich for max mileage. When the computer goes into open loop mode it’s spraying fuel from a “map” generated at the factory that says; “well, gee, hmm, were at 3Krpm, full throttle and 195degrees, lets dump X amount of fuel.” The fuel map in my Holley system was programmable from a laptop in the field. I seriously doubt that’s the case with a typical car. That system, and every efi car I’ve had, can’t operate fast enough to be as responsive as a carb. My efi cars have all been very sluggish at low rpm’s or of the line, and my Mercedes are among the worst offenders.

Re Lexus: Sounds complicated and expensive. I would break it for sure.