GMC Repair: Oil pressure gauge, oil pressure gauge, low oil pressure

Question
I have a 1988 GMC 1500 Siera. I normally only drive 5 miles, one way, back and forth to work each day. However, when I have multiple destinations and have to idle at stoplights, the oil pressure gauge shows low oil pressure and check gauge light comes on on dashboard. Usually by applying light pressure to gas pedal, to increase engine idle speed, light goes off and oil pressure gauge returns to normal.
My question(s): is this an oil sensor problem, or an oil pump problem? What would be a ballpark figure that I would expect to pay in order to get problem fixed?  

Answer
Hello Ron
this could be a idile problem if the rpms arr not high anough around 8000 rpm the oil light will come on . if you have a adj screw on the 88 some of them did you can turn it up and see if the light stays out on a idile.
the oil pump senser is ok .

If not adj screw then bring it to a shop so they can adj the idile . it is around 49 dollors for the serivice as to go on the master compuiter

Good luck with it . And if u need more help let me know .

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