Ok before you say it, yes yes, I have heard everyone say it before.. "Don't replace your plug wires they will fail... yada yada." I replaced plug wires on my previous car with no problems, and whenever my dad bought a used car it was always, plugs, wires, oil, tranny flush, radiator, bottle of engine cleaner, tires (if needed), battery and a long list of other things, not to mention the first "real cleaning." So i won't go quite as far as him, some things are fine until they aren't anymore, like a battery. And the radiator and tranny seem fine, although the engine compartment is a bit warmer than my Bonneville was. But anyway, Iam still on the gas mileage thing...
So Iam thinking Bosch Platinum +4s because most people say they are really good and a few have questioned whether they really do anything, although they havent ever tried them, and 'JIM' at Advance Auto Parts here in IOWA, seems to love them and he knows his 3800s let me tell ya what! and then of course some Bosch wires to cap things off.
What do you run?
Do you consider anything else to be better?
NGKs Iridium plugs?

No one says "don't replace the spark plug wires," they just say not to replace them with anything other than stock AC Delco because it will cost you more and last a shorter amount of time.

Scrap the Boschs, they foul way too easy. Get some AC Delco plugs as well, some pick copper others like platinum. I've also heard good reviews on NGKs.

BTW, how many miles you got on that tranny? Flushing might be a bad idea, but a fluid and filter change for it would be something to consider.

OEM plugs are fine as well.

I went with MSD 8.5mm's, because they're red and I've got a little bit of red going on with my car. The BEST wires to get will be OEM.
A solid core plug (copper) will aid in controlling KR. Plat's, or IR's will last longer.

Autolite plugs are good as well.

I got MSD wires a long time ago. They are a PAIN to install because they are a lot thicker than OEM, making it harder to fit into the stock channels.

I know you really want to fix your MPG problem and spend money on cool mods, but this isn't the direction to go. The stock igntion is very efficient. Picking hyped-up aftermarket parts here will only lower it. You want to spend money on mods that will make a difference.

Personally, I didn't get copper. I went w/ OEM plugs which are now iridium (original standard was platinum).

Now for your MPG issue. Others mentioned some very good suggestions. Check your O2 sensors, cat, and PCV. I really think it is the O2 sensor(s).

For those that would like some color and use the OEM wires you can get wire loom and cover the ugly wires and make them the color you want.

NGK Iridium = AC Delco Iridium

They're made for delco by NGK. once again the spark plug has been the spark plug fior 100 years, why change it?

o2 sensors... where might those be, one in the ubend right? now when I get that ubend deleted, should that maybe help?
and what other ones are there? So OEM is AC Delco? Iam not a huge car guy here.. but I try to understand.

Someone correct me if I'm wrong, but the O2 sensor that will help MPG is the front one. It's mounted in the exhaust manifold I believe.

Yes it's located at the top of the downpipe between plug 4 and 6. That one will affect MPG the most because the rear one is checking if the cat is performing as required.

Nothing wrong with changing something if you can do it better.

If that was the case, this thread would be made up of several pages, copied for each person on a parchment written via an ink quill and sent to everyone by a a kid with bag and a hat, running full speed.

So is there a concensus here?
Wires? AC Delco, Bosch arent gogin to be any better?
Plugs? Bosch are crap? NGK Iridiums? AC Delco?

Not saying they are junk just saying no need to waste your money because the OEM set up is just fine.

I recently changed my wires and replaced them with Taylor Spiro-Pro wires. They cost me $40 at a local performance shop. They are 8mm and they fit in the loom holders and work great! They also come in about any color you can think of!