Its an easy enough job and should take you 5-10 mins depending on how handy you are with the spanners, even in the dark. From the upper inlet plenum disconnect the MAP Sensor, Air Temp, Coilpack and Throttle Body multiplugs and then disconnect the plug leads from the coilpack itself. Note, the coilpack firing order, as you're looking at it is:
3 - 4
2 - 1
The lead position order, also as you're looking at it, is:
4 - 3 - 2 - 1
Remove the x8 10mm bolts that hold the plenum down (x5 on the front and x2 on the rear near the coil pack) then lift it clear. You will also have to oremove the brake servo vac line and the carbon canister feed. If you can't get these off do not worry as you will still be able to lift the inlet away to access the plug leads but you won't be bale to fully remove it from the area so it'lll be dangling there causing a bit of an obstruction to your view.
At this point it is important to ensure that nothing drops in to the exposed inlets... it will ruin your day if it does having to fish it out so cover it up with a cloth or similar to prevent this as accidents happen.
Remove the plug leads from the plug wells and with the aid of an inspection lamp/torch look down each plug well for signs of oil or water ingress. Any fluid in this area will give the ignition charge a better path to earth than the spark plug offers and so causes the charge to arc across the cylinder head instead of giving a good ignition source.... its fairly common on these after people have washed the engine down.