The lure.  The amazing hunting chatterbait from Seibert Outdoors to be specific.  I had no idea a chatterbait could hunt.  By hunt I mean actual hunting where is veers off course and then returns to center without having hit anything.  Real hunting and not that "it hunts when it hits wood" squarebill talk.  The 3/8 oz baits I have all do it.  You have to burn them on a 6:1 to get them to do it but they will also do it sometimes when stopped and started again and also spiral or zig zag on the fall.  Really awesome chatterbaits.  I think the hunting is from the split ring between the head and blade.  My hypothesis is that this allows for more movement and at high speeds the blade can over rotate at one direction or the other and lock causing the bait to veer or plane off to one side and then regain itself and track true then do it again.  

It's FOGY. one G. Otherwise we are all lost wondering where the bank is and scared to move while afraid to sit still....

I like the Fogy, but in fairness most chatters hunt or can be made to hunt.

The tremor does it also. Like you said it needs some speed burst and it goes really erratic. You’ll see it if you try to reel in a cast quickly instead of fishing it to the boat.