rite got a quick look at her over the weekend its runing on 1 cyilender the 3 one from left to right. i pulled the leads 1 by one when started and thats the only one that was runing so im thinking its 1 of 3 things the plugs the leads or distributer it hardly be anything else would it. thinking mybe the distributer is mybe corroded a bit inside mybe just an sand down a bit?
You'll probably find water has leaked down through the bonnet scoop and found its way to the plugs/leads, clean the lead ends up and put a new set of plugs in it, (not expensive for a peace of mind) also as another guy said, fuel: drain the old fuel out, if its been sitting there for some time it will lose its volatility, it will still combust.. But will run like a dog, might seem a bit silly draining the fuel out but,.. Old fuel can oxidise in the tank, and cause a sludge/gummy like paste in the tank, and that could cause you other issues, I'm not saying that is the problem mate, but its worth a thought before it causes you problems