Hard Start and No Power

[Sharon Papish <papishs@herald.usask.ca>]

    With the return of winter weather my 82 5000S is acting up.
It takes 3-4 attempts to start while the idle varies between 400-1200 
rpm.  In a couple of minutes it idles normally but rough.  After finally 
going the fun begins.  Acceleration is non-existant (city buses are 
faster and I have a gas engine) The maximum speed seems to be 40kph (25mph)
at which the engine shudders.  Rpms rarely get beyond 2000.  My mechanic 
cannot see it until Wednesday, so I am asking if anybody here has any 
ideas?
 Thanks,
 Derek