i have a 1997 dakota and every once in a while when i stop the check gauges light comes on and my oil pressure guage starts to go back and fourth. what could be the problem?

 

The check gauge light will illuminate for the following reasons:
- Bulb test (each time the ignition switch it turned "ON" it will illuminate for a few seconds, this lets you be assured the bulb works)
- Engine temperature high (coolant 253*F or higher, illuminated until temp drops below 246*F)
- System voltage low (less than 11.5 volts, remains lit until system reaches 12.0 volts, but less than 16.6 volts)
- System voltage high (greater than 16.6 volts; remains lit until system reaches 16.1 volts or less, but not less than 11.5 volts)
- Engine oil pressure low (0.5 psi or less, remains lit until pressure is above 0.5 psi).

When's the last time you had an oil and filter change (if it's been more than 3,000 miles, change the oil and filter)? Is the oil at the proper level?
If that is all OK, it's probably either: a faulty pressure sending unit (or, a fault in the wiring, causing the PCM to think oil pressure is incorrect), or a faulty oil pump (or items related to the oil pump)