Just reached 100k mi on my '98 5.2L ZJ Laredo 4X4. My "mysterious" surging idle had been behaving for some time, but recently came back. Heard that it's common for crankshaft position sensor to go bad, so thought I'd pre-empt a complete failure of it and possibly address the weird idle. Thought the factory shop manual made the change-out look doable. After exposing some lower levels of skin and using a lot of different tools--some of which I inherited from my machinist dad, I got the old sensor off. Examined the bell-housing-mounted, "3-sided" rubber grommet for construction and condition, and thought the lower shoulder would make it hard to mount the new sensor with grommet first mounted on the sensor. Thought the upper shoulder would hold grommet in place in bell housing as I pushed new sensor into place. Wrong!!! When I pushed on the new sensor, I guess I pushed the grommet into the bell housing!!! Questions are: 1) where could I get a replacement grommet? 2) even if I get new grommet, isn't it bad for old one to be in bell-housing? Even though it's just rubber, couldn't it damage sensor or flywheel gears, or??? 3) do I need to remove tranny and retrieve grommet, or??? 4) should I use a thin film of my synthetic, non-silicone brake parts grease first on the sensor next time I try to install it? [that grease claims it would not damage rubber or plastic parts (like the sensor housing and the rubber grommet?)] Many thanks in advance, Allpar-ers!!