My Idle is Nice and Steady
 

When I remove the oil filler cap my idle does not change. I remember years ago it used to change when I removed the cap. I don't think it's the cap o-ring because when I hold the palm of my hand over the tank it does not change either. Should I be concerned? Should I start looking for a vacuum leak? 87 3.2 48k miles.

Strange, it should drop a bit but I would check all vacumm hoses just incase.

I have some silicone lubricant with ether in it. Can I use that to check for vacuum leaks or is there a straight ether spray I can buy off the shelf?

If it idles O.K. leave it alone and don't worry. There is a restrictor in the line from the oil tank to the intake. And with a good working Motronic system the ICV should take care of changes in mixture resulting from opening the oil tank and compensate for it.

DO NOT use silicone spray. If you really try to chase air leaks use starter fluid, but be extremely careful since that stuff is highly flamable. Have a fire extinguisher near by and don't use it too liberal. Use tiny squirts and give it enough time for it to evaprate between squirts.

Ingo