Have had good luck with AC-Delco wires. Lifetime warranty and around $40. 50K and no problems. Easy to install. Wipe off the coil pack terminals with a clean rag and remember to apply the silicone grease to the inside of the boots at both ends of the cables.
The first generation LH cars with the 3.5L have a tendency to develop intake manifold gasket leaks which can also present as a rough idle and/or misfires. Listen for a hissing sound at idle with the the hood up.
Good idea to also clean the internal surfaces of the throttle body with solvent and a toothbrush. Buildup at the trailing edge of the butterfly valve will also cause rough idle. Can be done without removing the throttle body from the engine. Just remove the flex host at the inlet side.
I used to fix a "rough idle" on my Intrepid 95/3.5L with $3 fuel injector cleaner. Works for me. 170k miles on original wires do not have any reason to replace them yet...
I've had decent luck with Beldens from NAPA, ROTTEN luck with the crap Autozone sells, and right now I'm running a set of AC/Delco wires that look every bit as good as the Beldens.
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