My park avenue has developed a hesitation, mainly under load, going up hills. It sputters around 2000-2500 rpm and the tach drops off erratically. It doesn't do this at low rpms and it will quit when accelerating hard above this rpm range. I changed the plugs and wires (AC Delco) last weekend. Any help would be appreciated.

I read one forum that said this could be the Ignition Control Module?

any check engine codes? usually you would get some or the car wouldnt start with module problems on a 04.

I haven't had any check engine codes.

im not really sure, when i think of sputtering under load its usually a vacuum leak or lean fuel condition. so i guess i would check your vacuum lines, your fuel pressure, possibly change your fuel filter if you havent in a while. check your air filter too as long as your there.

a MAF. (mass air flow) sensor. Just had one go in my 2002 Buick Regal and it NEVER threw a code until the very end. By the time it did, it was stalling and acting up horribly. MAF'* are relatively inepensive and extremely easy to install. Yours is only 6 years old roughly: I seriously doubt it'* an ignition coil. Try removing and cleaning the MAF (see instructions in this forum: just do a search under 'mass air flow' sensor) If that doesn't work you can replace it, or just wait for the code to go off, because it will eventually.