If the problem only occurs in damp weather and disapears as the engine warms....
If you have an early(ish) V6 with the single coil pack on the right hand side of the block an easy way to tell if the coilpack is the problem is to lift the bonnet, start the car and spray the coilpack with a fine mist of water from a plant sprayer - if the coil pack is faulty you will see the sparks.
Be careful to keep your hands off the engine etc.
HTH
If you have an early(ish) V6 with the single coil pack on the right hand side of the block an easy way to tell if the coilpack is the problem is to lift the bonnet, start the car and spray the coilpack with a fine mist of water from a plant sprayer - if the coil pack is faulty you will see the sparks.
Be careful to keep your hands off the engine etc.
HTH