>>>*The Toyota pieces are pretty good when it comes to being balanced, it's a force of habit around our shop to check the weights though.

Lots of these engines have had folks there ahead of us, rods get replaced, things like that.

Balancing them is extremely easy, since the engine is vertical everything opposes, so just wiegh each rod/piston assembly. I have seen cases of the crank being out of balance front to rear but that is very rare.

Of course it is impossible to truly balance a 4 banger, all we can do is compensate, it takes 5 cylinders to hit true balance.

If your engine did happen to have a heavy rod or piston mixed in, this would explain a feeling that she is "missing" that is untunable, the comment about it going away with the air conditioning engaged is one I have seen before.

An exhaust emissions reading at mid-rpm's might offer another clue, also......*EB