hi there.... I'm a new member and this would be my 1st participation and cuz I'm not an english speeking I might be mistaken in some phrases or words So ibeg ur pardon...
I have an oldsmobile cutlass ciera s 1990 / 3.1L v6 mpfi .
the car work fine except that when the car get hot(normal operational temp.) while driving in city jam, if I chang the gear from D to N or p (stopped) the engine rpm start to go up (slightly) and down about 3-5 times till the engine shut down, when I restart it it works fine, this may happen several times in a day, never happens when A/C is on OR gear on D it just happens after changing gear from D to N and A/C off.
I would like to add that the type of feul used in my car is not good because in my country there is no other type but that.
in my country there is a huge number of my car type and other american cars but I havent seen such a problem but one car.
I hope that u help me...

 

start by replacing the coolant temp sensor Tell the parts store you want the one that controls the cooling fan PS Welcome to the site Larry vintageozarks.com

 

Thank u lary for replying, But I would like to know how the fan sensor cause this problem? And would be possible that the temporary high rpm (2000)when I restart the engine after sutdown to be causd by the same sensor too?