/6 sputters under load

Finally got back to work on it. Wanted to adjust the valves but stuff came up.

Was checking timing.....it started acting weird it was all over the place, 10* 12* at idle, at about 2K rpm it was about 30*.

Daughter reved it really high and when I went to check it again at idle it was reading 20*......what the heck?

Could this be a bad harmonic balancer? I have heard of them slipping and giving bad timing readings. What is the best way to check, pull #1 plug and check TDC and make sure the pully is lined up? Thanks all, Matt