At idle, I can notice a slight dip in the rpm as it is sitting there. Dealer checked it out a few times when I had it in and they said it is nothing, it is normal, or they can't duplicate it. I am planning to change the spark plugs and wires this week since it is over 100k now....thinking I would use ACDelco 41-110 but wondering if premium wires would be better. Any recommendations on the best wire sets to buy?