I'm going to purchase the BD3 scanner as suggested on this forum. I also read where the '96 Tacoma ECU isn't capable of displaying fuel pump pressure because it doesn't have a sensor for that function. It was said that a low fuel trim indicated no problems with clogged injectors or low fuel pump pressure. Can someone explain why that's the case? Would a high trim condition indicate a clogged injector or low fuel pump pressure? Thanks! Still learning!

Correct on the 3.4L V6 not having a fuel pressure sensor that the OBDII system can read..

Without reading the article, my guess is it was saying that the ECU is trying to overcome any deficiency in the fuel delivery system that is limiting fuel flow, for example low fuel pump pressure, by going to higher and higher values of fuel trim (increasing the fuel injector open time) to try to get the engine back to the ideal fuel ratio.

On the inverse, if there were leaking fuel injectors or other problem causing it to run rich, it would try to offset it by going to a increasingly lower trim values..

The oxygen sensor provides the key feedback in this self correcting closed loop operation. Guess you've already read this, but if you haven't it covers the topic.

Also easy to misinterpret "more" or "less" trim.. I prefer to refer to it as trim going to the rich side (to correct a lean running situation), or trim going to the lean side to correct a rich running situation).