ok soo my speedometer in my 94 z will just randomly not work...i will turn off the car and start it again and this will usually fix it. any ideas why its doing this or how to fix it?

 

The spedometer is controlled by the PCM, which uses the input from the VSS (Vehicle Speed Sensor). Check the wiring connection at the VSS, on the transmission tail, where the spedometer cable used to be. Look for bad connections, loose VSS, etc. If these are good, then it gets morer complicated, such as wiring between the PCM and the gage cluster, and the gage cluster itself.