I am inclined to think it is some electrical issue as well, that's why I qualified my post by stating what ignition I have and that I have OEM plugs.
Have you checked your spark plugs for indications of poor/weak spark?
An easy way to test your fuel pump would be to get a pressure gauge and tee it into the rubber discharge of your fuel pump. I think it should be 3-4 psi; I would have to look in the FSM to be sure. Having good pressure helps prevent fuel from vaporizing, so an electric fuel pump could help there. On the other hand, it may be masking other symptoms.
Rising Sun Bio
2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering,
no more Sanden OBA
1FZ-FE factory lockers +
Safari intercooled turbo, CDL switch, cup holder, Metric TLC leather, heated seats, JDM switches, PUMA OBA.
Warn M12000 waiting for a bumper.
Limited TRD 2UZ-FE SOLD