Ford Focus: Strange speedo problem

Can someone please help? I have a 2000 1.8Z, done 70,000 miles and a strange
problem has recently arisen. Driving along at any speed,suddenly the speedo
needle drops to zero, the radio volume diminishes and there is a slight loss
of power. This lasts only a few seconds then all is restored to normal. The
problem may not recurr then for either a few minutes or a few days but what
worries is that its not going to get any better. Please help.
Thanks. Tony Anderson.

A) sounds like it could be a vss.
B) if there is any other electrical items acting strange it could be a
temp. loss of voltage. eg. see if the inside light dims or goes out at the
same time. If so it could be a dirty ground cable under the air cleaner.
try moving the cable to the vertical inner fender just ahead of the black
bracket in front of the air cleaner. There is a hole w/ a slot for it but
clean the paint off lst and cover w/ grease ot weatherproof it.