Sorry to say but I'd start with a real FP test. It can be misleading looking at the amount that comes off the valve when you press it.
Being the plugs and wires are that new..I'd skip those. Codes would need to be read with a scanner that can do the obd2 plug with obd1 codes. And this one fact is a killer.
Your pcm is located up under the passenger kick panel of the dash. It actually lays on the floor/firewall. Has red, white and blue connectors. Try tapping on it a bit. Check the connectors.
Could be pcm, maf, iac, tps.
A bad pcm..well...let'* say you have one of the two flakiest pcm years.
Bad maf could tell the pcm too much or too little air. You can get it to learn the maf being unplugged and running off the tables by using a little throttle and keeping it running for a couple min.
Bad tps could again be telling the pcm to shut off fuel etc.
IAT shouldn't hurt it. Many of us have left them unplugged..it defaults values if the iat goes bad.
00 Regal GS: All kinds of cool stuff.