you didn't say that you replaced the spark plug wires. They wear out too. They are not like an electrical wire, an ignition wire is more like a capacitor in its design and over time the wire's ability to transfer energy, a well as its insulation that contains the energy begin to degrade.
The symptoms of degraded spark plug wires will be most noticable at start-up, idle and other light loads such as cruising.
Its simple and inexpensive. So even if it doesn't solve the problem, you won't be out alot of money and at 96k miles they're probably due for a change anyways.
