To lower a car the proper way, you need new knucles and/or lower ball joints with longer shank, which i think you didnt buy (because they are expensive
)
but at least you did the height change correctly. Did you get an alignment done since you changed the ride height ? rising the cars removes camber, toes the rear out and the front changes too. Which could explain why it goes all over the place.
Most of the time the car gets more controllable with closed hydraulics and very hard springs... the only reason for that is a very bad suspension. Locking it in place makes you run all the time with the static settings. Which again is not good, because the static settings are supposed to be made so the car handles when the suspension is working.
Anyway... if the car is still all over the place, close rear hydraulics a bit more.