check intake plenum boot
Just changed plugs on my 1999 aurora and the gap was .05. It stopped a hesitation at idle too!
Its located on the back of right cylinder head ...fun too get too.....
Bad idle may refer to many things. Generally it means the idle is too high, too low, or there are misfires.
Mine idles at 69 and drops to 55. I too wondered about that.
I have a 1995 Aurora too and it runs at 220. I am the second owner and it has always been like this. I think it is running too hot. All my other vehicles have always been under 200.
Idle adjustment set to high
Too high of an idle could be producing too much fuel for your jets to work with
the engine runs at a faster rate than when the idle speed is lower.
The idle speed is factory pre-set, and no adjustment is available. If the idle is too high, or too low, you will be having other problems that will affect the idle. In cooler temperatures, it will take the engine longer to come out of fast idle, as the engine warms up to operating temp. If the idle is too high/stays at a higher than normal idle, then take the thing to get it repaired. Running a car in gear(automatic transmission) with a higher than normal idle, can damage the transmission.
Idle speed is not adjustable. It is controlled by the engine copmuter. If your idle speed is too high or low you have a problem with a sensor or the idle air controll actuator. Also, a weak battery can cause the idle too be erratic
You may have leak in the intake
P0507 : Idle control system, RPM too high.