Hi all, been having a very large idle problem with my vg33e for a while as its been sitting in my yard waiting on me to figure it out. I had it at one point running smoothly but after tearing it down so many times I feel it could be a slew of things. Currently the idle rhythmically surges up and down and is making it impossible to ensure my distributor/cam timing is correct, so here's my questions.

When replacing the TB and setting cam timing, one should turn the engine by hand a few revolutions. During which, are the timing marks supposed to line back up if done correctly?

If my cam and distributor are correct, my next thing to check was the tps. I set it to .5 volts and at WOT turned to 4+ volts, yet when I started the vehicle the volts would jump from the measured voltage to random voltages, is this a bad tps and is it producing my idle issue or is it a byproduct or non related?
May I include that after testing tps, with key on engine off, and throttle at mid range there is a buzzing coming from firewall area on cylinder 1 side.