Speedometer works intermittently

There is a plastic gear in the speedometer that eventually breaks on mechanical speedometers called an odometer drive gear. This will involve removing the speedometer from the instrument cluster in the dash.

Nope. The speedometer needs a signal from the vehicle speed sensor to operate. Is the check engine light on? If so, scan for any codes that may indicate a VSS problem. If no codes, possible internal cluster issue with the speedometer head

My parents had the same problem with the dash lights on there Montana. After 7 trips into the shop we determined ourselves that there is a wiring harness that runs under the carpet on the drivers side in about the location where most people rest their left foot when driving. What was happening is the wires had worn through the insulated cover and was grounding out on the bare floor under the carpet. We were able to tape the wires and wrap them with hockey stick tape to prevent it from happening again. It is worth looking into.

check that the throttle plates are not all carboned up. The 3.4 and 3.1 l gm engines are know for that. I have seen no starts or hard starts hot for that problem.

unfortunately you can't..

When the gauges quit, does the ABS light come on? Does the gas gauge and temp gauge quit too?

Hello Durham.
Couple of possible problems here.

Does the odometer work? If it does your speedometer is defective and will need replacement.

Or if your check engine light is on your speed sensor or wiring will likely be the issue. This will also affect the odometer.

inside the door panel for the module ,speedo lights and fuel gauge is another problem

Here's a link to your fuses,if the wire inside fuse is broken,then it's bad. Interior Fuse Box Location 1997 2005 Pontiac Trans Sport 1998 Pontiac...