check guages light on 1999 Dodge Ram 2500

when I am traveling its fine but when I come to a stop or almost a stop the check guages light comes on and the oil pressure guage goes down, once I accelerate the light goes out and the pressure goes back up.This happens often when I stop or almost stop I cannot figure out what this is.Can you please help me.If there is a part to install please inform of where this part is located.

Asked by for the 1999 Dodge Ram 2500
Check your oil pressure sending unit, they often go out on Dodges.