can't turn key sometimes

This is kinda ironic in my situation, because my fathers ex-police car starts without a key.

Mine however, sometimes won't even TURN with the key in it.. It's not a copy, it's an original GM key that came with the car, and sometimes I can't get it to even turn or unlock the wheel.

Since it's an original key it may be worn and isn't fully engaging the tumblers inside the ignition. Do you have a copy laying around anywhere? Or even another original? If you do, try one of those. If it still gives you trouble even with a different key, the problem lies within the ignition itself. If this is the case, then as long as you don't have the little chip on your key, try squirting some penetrating lubricant into the key hole. Sometimes things like to stick. Worst case scenario would be that you have to replace the ignition, which is actually a fairly simple and not-too-expensive thing to do assuming you have access to a steering wheel puller.

Since it's an original key it may be worn and isn't fully engaging the tumblers inside the ignition. Do you have a copy laying around anywhere? Or even another original? If you do, try one of those. If it still gives you trouble even with a different key, the problem lies within the ignition itself. If this is the case, then as long as you don't have the little chip on your key, try squirting some penetrating lubricant into the key hole. Sometimes things like to stick. Worst case scenario would be that you have to replace the ignition, which is actually a fairly simple and not-too-expensive thing to do assuming you have access to a steering wheel puller.
Mine does have PassKey, but I do know how to modify that if I have too. I know the resistance of my key's resistor, and can place a permanent resistor in the ignition switch if I must.

Do you have any more keys than just that one?

Do you have any more keys than just that one?
only one key..

go to a gm dealer and give them your vin# and they will send you a new set For $200 smackers, had the same problem with a 96 sonoma sls
Damn passlock sytem!!!!!!!!!!!

thank god mines too old for the passkey BS.

Since that is your only set you can't even get it copied because if you do the worn teeth in the key will be copied into the new one and doesn't solve your problem whatsoever. You might be stuck paying the $200 for a new key. Or you can go junkyark hopping and find another ignition for cheap.

Or get a new VATS lock cylinder for about $45. That's what I paid about a month ago for an Olds (same column/lock as a Caprice).

Your other option is to lube the lock cylinder with powdered graphite and work it into the plate tumblers.