i have been reading your postings with interest, since I am having a similar problem....I am experiencing a loss of power on acceleration...changed the plugs, rotor, cap, ignition wires, fuel filter and also flushed the injectors...the problem still persists. My mechanic now suggests that it might be one or more of the fuel injector that might be bad. I also have a 1992 ES300...automatic.
Would really like to know the outcome of your trip to the dealer......