I just purchased 97 4Runner Limited with 3.4l engine. Several times during my 800 miles trip low oil pressure light came on right after I stopped at idle. At about 700 rpm it was on and was off when rpm went above that. I checked oil level several times during the trip and it was full and engine does not appear to burn any oil. I was driving it before on short trips and had no light coming on. I just have a light for oil pressure monitoring and no gauge. I was wondering what is the best way to deal with it. Should I install new sensor and observe behavior or should I get a gauge and sending unit? Thank you for all your help.