It may be a little more than just the fuel. With the Ford engines there are often problems with the plugs because of water that leaks past the plug caps and is deposited around the sparkplug. It is a common cause of low rev misfires and difficulty in starting.
Yes Peter suffered a bit of that on the way home during heavy rain but soon cleared.
Looking at Cosworth Coil cover but at £194 a bit steep for a bit of plastic. But if it didn't keep going and I had to dry out or change the plugs it would be the best £194 spent!
