Yesterday, the car started to run on 5 cylinders, very lumpy and massive smell from one of the CAT's.
Today, I replaced the plugs, hoping it was a dodgy plug. At the same time, I took the plenum off, cleaned the throttle bodies, inside of the plenum and the breathers. To be fair, the breathers were very clear anyway, but as it was in pieces, I gave it the full treatment.
3 cans of Carb Cleaner, and a lot of rag later, everything shiny like new. Re-assembled everything and fired her up. Still running on 5.

A few phone calls later, and a new DIS-Pack is looking like it's going to be £135+VAT, but I'll have to wait until Monday to get one.
One final call to a good chap in Bristol (Gary, Kingswood Cavaliers) and he has genuine DIS-Packs on the shelf, £100 cash

I tell him which one I need (model number ends in 107 I think) and head up to collect.
Nice shiny new DIS-Pack in hand, I drive home in a horrible Peugeot 106, and get to removing everything again.
This time, removed the Wipers and Scuttle panel for easier access to the DIS.
Managed to remove it in under an hour, some shouting and screaming, but hey-ho. New DIS fitted, re-assembled everything, and fired up..... PERFECT.
New Plugs and clean Throttle Bodies have made a noticeable difference to performance. Just seems to pick up and go like it should, no hesitation, no flat spots. Awesome.
A quick pic of the Old and New DIS;

It's not the nicest of jobs, but for anyone who needs to tackle this job, be sure that it isn't so bad as it seems.
