Monday morning on my way to work my SES light would flash about 8 times upon hard acceleration. I thought it was going to be my fuel pressure regulator again. I pulled into Autozone as I had my codes cleared there a few weeks ago and figured that these would be fresh. It came up "random misfire," "O2 sensor" and "rich fuel mixture." SES light stayed on for the whole week and had rough popping idle. Thursday night, after dark I opened the hood just to see if I had a bad wire. I had a lot of bad wires. There were blue sparks arcing all over the place. Today I picked up a cap rotor and wires and replaced them and the connections on 4 of the 6 wire connections at the distributor cap were rusty and corroded. I just replaced all this stuff in February with a $350 tune up. It cleared up the problem. Apparently those rubber boots on the distributor cap are not weather proof. I am going to keep a better eye on those wires.
Just thought I would share this tidbit of info.

 

Did you use spark plug wire grease in the boots? When I replace a set, sometimes it's hard to get the wires to SNAP on the cap becuase there's a good bit of grease in there. That keeps the contacts from getting rusty. If they didn't have any, you can get a small package of it at autozone or advance. I think the brand name is "just enough". Hope this helps.

 

My Blazer has that bear claw style distributor cap and I can see the guys point from a post from an earlier thread. I noticed that some of the boots try to push themselves back out from trapped air when pushing on. I used his idea of a small thin screwdriver to let air escape whilst attaching said boots. I took the beast out for a beating today and pushed it real hard and the SES light is off and stayed off and it is still running and idling like new. I am wondering now if that whole fuel pressure regulator thing was not necessary or that I just moved the boots on the cap when I removed the Plenum a few weeks ago. Probably why it ran good for a couple of weeks after. Then the connections in the cap went south again from the corrosion. It's all good now!