The unfixable mystery problem

[btwilson86]

It sounds to me that the air entering the engine is not being metered properly. I haven't seen much discussion of the possibility of a bad mass air flow sensor in this thread. If the sensor is bad, or if the wiring has been reconnected improperly, your computer will not be receiving an accurate measure of air and will not add the proper mix of fuel, therefore resulting in a loss of power (stopping you from increasing your rpm's with various loads). Note that you will still be able to rev in neutral or park as there is virtually no load on the engine, thus requiring little power to rev.

I tried finding a pinout of a N/A mass air flow sensor, but have failed in the search. Colored wires should be the same on similar year supras, so you might be able to cross reference that way. I say swap your Canadian MAF for your CA one and see if that helps.