Volvo Repair: Electrical problem 1996 Volvo960, 1996 volvo 960, temperature guage

Question
Sir, my 1996 volvo 960 shudders(constant vibration) when I'm driving. When I accelerate the temp gauge dips to zero. This car gave no trouble for over 250k miles, then the timing belt broke,had the engine repaired, works beautiful except for this electrical(that's what I think)problem Any thoughts on a soloution?      
               Thanking you in advance
                             Marva Callender.  

Answer
there are really many things that can make the car vibrate.the temperature guage could be a bad thermostat,or bad coolant temperature sesnor which is located in the thermostat housing.the vibration could be bad tire worn engine mounts misfire of some kind wither eledctrical or fuel related like a bad injector.depends on what you mean by vibration.it should really be looked at for a proper diagnosis.