steering wobbles on hard landings.

How fast were you going? I've seen me being almost stationary on some landings and the bike is totally unstable.

If this is the problem, no amount of tinkering will solve it.

If not, I would check that the clickers are set the same on both fork legs and the oil level is equal.

Yeah move to the back of the seat and grip the tank real good with your legs , or maybe the front end is a little too soft or too low in the clamps .Did you ever get the suspension serviced ? Alot of guys like to use steering dampers for the same problem youre having . When you take a bike thats pretty soft and compliant and point it at nasty stuff it may get a bit unstable , A damper helps to keep the front end in line a bit .Sort of helps to let you use soft setup without compromising some stability.If you need to firm it up that could also be a problem like if youre a larger rider with soft springs or the original springs are sacked out etc. Some fellows like to grease the steering head real good and add positive preload on the bearings to give a little drag , but only if theres good grease in there . Some guys also like to put a grease fitting in the steering head also to grease after a wet race or run . You probably know this but too much forward weight bias will make a KDX unstable , If you have the rear end jacked up or preloaded and front end sagging down the bike will try to swap . Before anything else I would try to adjust the steering head bearings correctly and raise the triple clamps a bit .Maybe a bit more oil or a bit of air in forks might help ( if air forks) .

Conventional forks are known for FLEX !!