The upper intake manifold gasket and/or a PCV vacuum lines/hoses can develop vacuum leaks with age. This type of leak can result in a higher that normal or rough idle.
Average mileage: 159,770 (95,568–211,678)
Engines affected: 3.1L V6, 3.4L V6
24 people reported this problem
I have a 93 olds cutlass supreme 3.4 DOHC it sat thru winter and the battery died. Since getting running again it idles high and wont come down. I was told probably IAC valve and when I checked it with the key on the plunger popped off. So I got a new IAC and installed it. No change I then installed a new TPC no change. I checked for vacuum leaks and id not find any and no whistling .What is wrong with this thing???
At first it was just a rough idle I took it to get it repaired and now it's been extremely rough idle that sometimes is idled way too high and when you give it gas it immediately cuts off .It actually hasn't been repaired yet this just happened but I took it to the local mechanic that I use and he replaced all the vacuum lines and now the car cuts off every time I try to drive it it's not even usable at the moment so something they did made it even worse by far already had intake gaskets all transmission seals air-conditioning system electric fan motor Engine mounts emergency brake brake rotors replaced spent $3900 to give car to my son for graduation and now it doesn't run