Low Oil Idiot Light issue

Been having a strang issue with my 97 Grand Voyager. Will be sitting at a red light with the transmission in drive, RPM will drop to about 600RPM and then the red oil lamp on the dash (idiot light) will start to flicker and the warning chime will start sounding. If I drop it in neutral the RPM's go back up to normal along with the oil pressure and all is OK.

I'm topped off with oil. What I think is happening is the RPM starts to drop and thus the oil pump slows dropping the oil pressure. Other than the above issue the 3.3l engine runs like a top! What component should I be looking at replacing?

Ideas, suggestions?

Robert
(COLD) Concord, NH

All things considered, unless you have a direct pressure gauge, I would replace the oil sender located to the left of the oil filter. They run about $20. If you have access to a gauge see what the true pressure is before you spend a buck. AutoZone may let you barrow one for a deposit.

What component regulates the idle? It's not the oil sender, it's the oil pressure. If my van stays at the set idle point I'm OK, it's when the idle drops is when I have the oil pressure issue.

Idle speed is controlled by the PCM. The signal from your oil pressure switch is not an input to the PCM like a TPS or a MAP sensor. More than likely the switch is faulty; but the only way to know for sure is to check the oil pressure with a manual gauge as was suggested by RIP. IFIRC the light will turn on if the pressure drops below 3 to 4 psi at idle. Pressure is also ck'd at 3k rpm and should beat least 30 psi. With a good scan tool you can watch the idle speed in relation to the step postion of the IAC and with some engines timing comes into play to control idle speed. Accessory load such as A/C;alt duty cycle; rad cooling fan duty cycle and gear position all have an affect on idle speed. The first thing to ck is the oil pressure with a manual gauge and be sure there is not a problem with the engine.