Something weird just started happening with my galant. I have no problem or maintenance lights while operating the car normally. When I come to stop now, or idle, after driving around is when i get this problem. The Oil maintenance light sputters on and off repeatedly, but not wholey. The light comes on very dim, then fully illuminated, then dim again, then off, then this repeats randomly (while im waiting at a stop sign or red light). This is in sync with the tachometer dipping way below normal idle as soon as I come to a stop, causing the car to shake and rumble as the RPM's dip, rise back, dip, etc etc. As soon as I accelerate and drive the car normally the Oil Maintenance light and Idle/stop RPM situation goes away and doesn't return again until I come to a stop/idle. What gives amigos.

start by cleaning your throttle body. that will alleviate your idle issues, and may take care of the oil light issues, too (assuming the pressure drop is due to low RPM).
however, failing oil pressure switches are fairly common, so you may need to replace that as well.

i had a feeling it could be to the throttle body, my friend also mentioned somethng about replacing the fuel filter. Um you think you could explain a little more on how to clean the throttle body. Thanks.

Something I forgot to mentioned that is really strange. The problem I am talking about above is much more prolific after driving on the highway or at high rates of speed. When I am using the car to say drive around town to do some errands the RPM dipping/Oil Light issue at stop/idle doesn't really occur. When I drive on the highway and then get off is when the problem happens at every red light or stop sign. I cant explain that. But I did clean the throttle body today and test that theory. It seems to have slightly improved the problem, but it has not solved it completely as I experienced the RPM dip/Oil light at red lights after I got off the highway.