Help! Jetta 2 problems-not scirocco

[SCIROCCO75 at aol.com (SCIROCCO75@aol.com)]

Hey my 91 Jetta 8v has started doing something weird, it is incredibly cold 
here in Michigan lately and I found my engine temp gauge heads back to cold 
when I am on the highway, the faster I go the colder it gets until it pegs out 
(no reading) then the engine starts to loss power, it feels like its running out 
of fuel. When I slow it down to 55/60 the gauge starts to budge again and the 
power comes back.  The heat seems to work fine regardless.  Is there a bad 
temp switch fooling my dinasaur ECU?  Or maybe I have two seperate problems that 
seem to coincide? Please help, This is a primary car for us! Thanks in 
advance, Michael