After writing my last post I have put about 350 miles on the park ave. And it still has the hesitation while accelerating at high speeds 55-70 mph. Anyone have an idea what that may be?

I found the issue causing my hesitation issues and wanted to share. In the case of my 97' Park Ave... The people who owned the car before me installed new plugs and wires right before I got it. That was around 25k miles ago. I'm not sure what the plugs are yet because I have not removed them, but they told me they were cheap copper plugs. The wires were Autolite professional. I replaced the wires with AC delco OEM wires from rockauto.com. Problem solved. I also bought some AC delco iridium plugs from the same site but the wires solved the issue. I am hoping my milage will improve also from 23MPG. Can anyone tell me how long copper plugs usually last?

For better exposure and replies, I created a new thread for your 97 Pk Ave hesitation issue.
I am happy the new wires fixed the hesitation, Thanks for posting !

The Iridium plugs are very long lasting plugs, and work well in the 3.8.
I still change my iridiums every 50K miles though. Make sure you still check the gap and set them to 0.060 inch as required.

Copper core plugs do not last anywhere near as long. At 25K miles, you might as well go ahead & replace them now. I think you will find the fuel mileage may increase, once the new iridium plugs are installed.

Once you have the old copper cores out, measure the gaps on the old ones too, and see if they were out, or even close to specs.
Post a photo of what they look like as well please. We can tell a lot by the burn color/ condition of the old plugs.

I have never heard of anybody having good results from using copper plugs in our 3800 II'*, let me clarify, I have heard of more issues with them opposed to without them.
Platinum should work ok, but I always go with Iridium, it is what was put in when the car was manufactured.
As Art suggested I'd go ahead and get rid of the copper plugs.

I will change them soon. Anything I should know about getting those rear ones out? Looks like it may be tricky.

I have installed the new plugs. The ones that were in it were champions. I checked the gap with calipers and they were dead on .060. The new ones were ACdelco 41-101. These were pre-gapped and also dead on. The ones in back were not as bad to get to as I thought they might be, But not exactly easy to reach. I've posted pics of the champion plugs I removed as requested.

Good Work ! The park Ave will like the new AC Delco iridium plugs you just installed!
They all look normal except The 4th photo in shows some fouling, rich/carbon. Now with the new plugs & wires that potential misfire should be done now.
It is good take take a rip on the hwy to heat the plugs up/clean em up, if you do a lot of city driving.
I think now you are good to go!

ALWAY* use OM plugs in GM cars......yes that one plug did look fouled......chances are you had a misfire rather than a hesitation....

Glad you got them changed ok, some put a thick blanket on top of the motor, and lay on it to be able to get to the rear plugs easier, I always seem to end up with a bleeding knuckle or two from pulling the wires from the plugs, removing the plugs seems to go easier.
Good plugs to get, those are the ones I have used in my 96' Park Ave since it was made, cannot go wrong with those OE Delco'*, E3'*, or NGK'* are also decent plugs, but I prefer my Delco'*.

Here is a decent link on plug wear.
http://ngksparkplugs.com/tech_suppor...qs/faqread.asp

Yeah the hardest part for me was when I dropped my socket and it went in between the exhaust manifold and block in the rear. It took me a while to fish it out with a magnet. One thing I noticed is that the rear boots have metal heat shields on them and the front ones don't. Should they be on the front? Or is there just more heat build-up in the back and not necessary on the front. Also, the number 6 wire is really close to the o2 sensor. I read that can cause issues. I routed it so it couldn't touch the sensor but it is touching the wire coming from the o2 sensor. My Park Ave is running fantastic though so no issues yet.