Just had a great drive in my '89 XJ-S today. About 100 miles of interstate to stretch the cat’s legs! My car is running very well and ate up the pavement at 75MPH+!!
I noted that right after I got of the highway and arrived home and put it in park it started idling a bit lumpy between maybe 800 and 1000 RPM. I put it back in drive and the idle smoothed out immediately. Then I left it in park running and within 2 or 3 minutes it was idling smoothly there too.
Any ideas what caused a lumpy idle after a highway speed drive but only when the car was in park and only for a few minutes at that? Thanks for any ideas!
I will note I never have any idle troubles any other time. It starts and idles smooth at about 1100RPM when cold and once warmed up automatically drops to a ~750RPM smooth idle. Also, it’s fairly cold here today, think I experienced this at about 28F outside.