3rd Gen 3.4 motor, dash and full wiring swap into a 2nd gen
 

Would it be pretty straight forward to swap a 3.4 motor, full wiring harness/ecm, dash, relays, fuses, window motors/switches, etc. into a 2nd gen 4runner? I have a 2001 limited auto, would like to swap it all over into my 1990 4runner because its rust free, solid axle swapped with 4.88's and a 5 speed. Thoughts?

There is an entire forum devoted to 3.4 swaps. https://www.yotatech.com/forums/f160/

It doesn't sound that easy to me (body lift just to get the engine to fit?), but I've never done it, and many others have with great success.

I am considering the same idea with mine, T-100 3.4 automatic to a 95 4Runner auto. The only difference is that I plan to include the transmission and t-case if it looks doable and my 4Runner is fully loaded while the T-100 isn't.
Keep me posted and maybe make a build thread to cover what you do if you go this route.

Will do, thanks!