[Gearhead999]

First things first. Slick 50 is crap. Just snake oil.

If the "knock" is only in morning we need a little more info.

Did it knock before you changed the lifters?? If not, you have a valve[s] adjusted wrong or a bad lifter. Yes, new ones can be bad.

If it is deep in engine, and you had it before work, sounds hollow and goes away when warmed up. Could be piston.

On the rough running. I agree check choke. Also, if carb is leaking down overnight the fuel is in the engine and fouls out the spark plugs. This causes roughness on first start up and cleans itself out after several minutes.