All the wires are hooked up to my radio correctly but when i crank my car or turn the key back the radio doesn't come on. then when i cut the park lights on the speakers make some kind of flickering noise until i cut the park lights back off. whats this?

the dash lamp IMMO will not lie, it tells you if the key is good or now, covered in the free users guide.
but use the IMMO can lie of battery is near dead. sure.
not told what the gear shifter does,
what does CUT ON mean? (radio dead or works/)
the steps are easy cart like this auto transmission
we can crank the engine in park or neutral if we step on the the brake pedal, the lever moves. at your demand, called park lockout feature
I get it ,does nothing means the starter is 100% dead
while key turned (cranking) in PARK.
turn the key to on /run position the IMMO lamp talks to you now, it tells 2 things key good or key bad
if bad no immo car will ever start. or starts for 1 to 10 seconds and stalls.
if the battery is dead or failing many things will word and not work, for example radio works but the starter is dead the starter uses 1200 times more power than the starter.. so radios can work. with near dead batteries.
for 70 years true.
so, check battery lugs for rusty or loose
charge the battery and load test it.(in a shop)
or buy the tools.
or jumper cable jump the battery.
or call AAA auto club tow,and say jump start me car.

also learn that IMMO can lie to you if battery is weak.
answering for NO CRANK cars.

there i lots more to any starter, the permissive's
here is the list (and voltmeter tests for each)

1. battery good. 4 lug ends clean and tight. no rust.
2. all fuses good (oops forgot all those?) cab/bay all.
3. key gets 12vdc power and ST pin goes hot cranking.
4. PRNDL switch closed for park IF FAIL CRANK IN NEUTRAL
5. OK STARTER RELAY CLOSES.
6. NO IMMO FAILURES, lamp on dash happy.
7. starter solenoid small lug goes hot, 12vdc
8. starter cranks if not bad. or engine not seized.
9. any tech knows how to hot wire any dead starter (keys in pocket)

immo mostly cuts spark then fuel but some rare cars cut ALL
if battery is bad, yes head lamps prove little, we jumper cable crank all dead starter now, watch the tow truck guy see?
Heads are 10amp starter is 300+ amps, apples and oranges not the same, see?

or get the car fixed in a shop as 99% do.
learn and do or get it fixed.
guessing fails mostly, use a voltmeter find the path to the point of failure,
keep that new battery charged or now you have 2 problems to fix.

I am not sure about the pig tail issue my advise find another impala 99-03 and verify the wiring issue, the other issue sounds like a body control module (BCM) if your BCM is completely malfunctioning that will explain the no crank and the power issues. Before you go replacing your ignition or pulling out your hair you may want to take it in and spend a few bucks to have it hooked up to a Tech 2 (generally only GM dealers have those) and verify. This is my best educated guess from the symptoms you have described.

Sounds like an Ignition Module or similar device. Does it have an alarm? Turn the key to ON - not start - and put into Drive and then back into Park. It may be the shifter isn't fully engaged. Also, w/your FOOT ON THE BRAKE shift to Neutral and try to start it.

GL,
Td

get a wire tester. One end has an alligator clip the other looks like an ice pick with a light in it. put the alligator clip piece on a grounded object. Turn the key on. Poke the ice pick end onto each wire. the wires that cause it to light up are the hot wires (power going to them) sort them out separate. now turn the key off. Which ever of the power wires doesn't light up with the key off is the wire that turns the radio off with the key. However the main (usually yellow wire) on the radio need to be hooked to a wire that has constant power as thats what stores all of your stations and keeps the time on the clock.

ur wires are shorting out

I have the same problem did you get it fixed if so what was the problem

Check power distribution panel near battery for blown fuses.

Pull it back out, (Radio) and recheck your steps. Something is not hooked up right. When you pull it back out, See if it goes back working normal. Retrack the wires. You cut are hook up something wrong????