MK1 Cab Cutting Out

I have a 1983 golf cab 1.5 auto which occassionally cuts out. When it cuts out there is a clicking noise from the fusebox. The fusebox is new and I have a new carb. It tends to happen mostly when I am going down hill or have not had my foot on the accelarator for a while?! Although sometimes it just does it when I'm driving along. Any ideas?

Do you have an immobiliser unit fitted?

No, but got an alarm?