Speedo/MFA issue

[Reverend Frog 10]

So after having the sparks and HT leads changed recently on my 1993 VR6 (later spec clocks with the red needles )my speedo is starting to play silly buggers:

 

What happens:

 

• speedo needle doesn't move at all for the first 5-10 minutes of the journey
  
• then it twitches and comes back to life
  
• while it's dead, the odometer, trip meter and spoiler do not work either
  
• same for the MFA's average speed and total distance functions
  
• additionally, the oil temperature usually doesn't work, and when it does I suspect it's too low (never goes above 80 and seems to drop too)
  
• the MPG is always at 99.9
  

 

What am I looking at, do you think?

 

Cheers in advance

[dr_mat 0]

Voltage regulator on the instrument panel is a common failure I hear.

 

You may find this also coincides with an alternator or regulator problem that end too so the supply voltages are not reliable. This is often because the blue "exciter wire" is going bad between the battery and the alternator's regulator.