Is it necesarry to have a kickdown cable if im running a 2000 stall and a shift kit with my vehical?

All the kickdown is for is to shift to low gear when you go to accelerate. Like passing a car on the high way.

i'll assume you have a TH350 and not an overdrive like a 700r4 or 200-4r..
on a TH350, you just unhook the kickdown and not have any problems.. but why would you want to?

reason being when I accelerate my car, it down shifts( to 2nd) revs to about 4800 shifts, then it will shift (3rd) then at 5200 rpm it down shifts throwing my engine to 5800+ rpms what can be my problem?

You can udjust the cable on your throttle linkage to where it will only shift at a certain throttle position. Just adjust and experiment until you get it. You can buy an adapter if the kickdown cable is to short.

reason being when I accelerate my car, it down shifts( to 2nd) revs to about 4800 shifts, then it will shift (3rd) then at 5200 rpm it down shifts throwing my engine to 5800+ rpms what can be my problem?
sounds to me like the driver has a foot made out of lead.