'99 silverado will turn over but won't start. I have a new battery, 6 month old starter, new plugs, new distributor cap and rotary button. I used to be able to turn the ignition on and off real quick and it would start, now this doesn't even help. Once it starts it would continue to start fine the rest of the day. Any suggestions?

I'd start with one of these and move on to the next.

Fuel
Spark.

Is it getting fuel? You should have an "in tank" electric fuel pump. When you turn the key halfway (just before turning the engine/starter over), you should hear the fuel pump prime. Easy way to check is to look in the throttle body while someone turns the key to the "on" position. You should see/smell the fuel. You can also listen to the gas tank while the key gets turned. You should hear the fuel pump run.

To check spark, pull a spark plug out, put it back on the plug wire and rest the electrode end of the plug up against the engine or exhaust manifold and have someone turn the engine over. You should see the spark plug firing. Don't hold the plug or wire while doing this. You'll get zapped if it's working ok.

If these both check out ok, then take a look at your firing order. If it's off by a significant amount, it may not fire. I've seen this happen when a cap/rotor/wires were changed and the wire/rotor was not positioned on the correct cylinder. (Most of the time they will at least fire or backfire, but either not stay running or run REALLY badly if the firing order is off.