Working on a 2000 Lexus RX300.

The engine cranks over but won’t fire up. I have replaced multiple parts after running tests, and some I replaced as a regular maintenance replacement. In addition, I’ve tested that it does have spark. It now has fuel getting to the fuel rail (after replacing the fuel pump). I tested all cylinders and it has good compression. Timing belt in tact and motor timed properly. Replaced EFI relay and fuse. The engine does start when I spray starter fluid in the intake. And yes…there’s fuel in the tank. 🤦🏻‍♂️

Parts that have been replaced, and reasons:-Fuel pump (Old pump not working)
-Fuel filter (Old filter clogged and old)
-Fuel injectors (2 out of 6 not working properly)
-Fuel pressure regulator (Preventative maintenance)
-EFI relay and fuse (Cause why the hell not?!)

I’ve been a mechanic for over 28 years and this one has me stumped pretty bad! Is there anything that I’m missing? I mean, what could cause this thing to not start? Any help would be greatly appreciated! 🙏🏼