Hi Saumil -
Thank you - I will check into that.
My idle hunting problem came back again, out of blue. 800 to 1,800rpm, up and down rapidly and repeatedly. So, I took my propane out, with rubber hose attached, to fish for a vacuum leak. Propane did not do anything but I must have touched something while I was doing this - car started to idle perfectly, all the sudden (without any help from propane). I am beginning to think there might be a frail wire, as this happend when my hand touched wire harness around the throttle body.
I hope I can re-create this scenario.
In older thread I read, there was a mention of vacuum line running from intake to auto box to cushion a shock from gear engaging. Is there one on 87 W124? I really should check that also, as my trans engages little harder than I like, even at 800rpm (very hard at 1,500rpm). While I cannot be certain, I feel rpm surges when I shift from park to any other gear. Could this be happening?