90 xj idle issues -too high&low

I've got a 1990 xj...
Starting on Friday I noticed it was sitting at 1000rpm in D and 2000 in P or N.
This isn't happening all the time. It usually sits at 5/600 regardless of the gear when stopped. It also pulls more and is hard to brake when its idling higher.
This happened two or three times on Friday and it doesn't start and run high it just starts doing it randomly during the drive.
Today now, twice, it has started fine I've driven 100ft and its stalled.. and then when I start it again it idles at around 100rpm for a couple mins then is back to normal....

I replaced the 02 yesterday and fuel filter last week all the fluids are in good shape and the only coolant issue I know of I a very small crack where the upper rad hose goes in. Its in that area, it doesn't leak coolant though.

Please help!
-kerri.

Since this is your first post, I will point out that your best info will come from reading the threads that come up at the bottom of this page.

I only have net on my phone right now so its not very easy to go through tons of threads... plus the bc4x4 guys told me to post here.. I'm a reg there

First, If you want to get right to work, start by looking for vacuum leaks. High idle is a classic symptom of sucking air somewhere. XJ's are notorious for intake/exhaust manifold bolts working loose. The next thing would be to check your grounds. The one next to the dipstick and the one from the head to the firewall are the biggies. Don't forget to have a look at the much maligned TPS sensor. If your up for some reading the thread entitled "renx files" is a long thread but some very important and helpful information in there.

sounds like the TPS sensor to me

good luck!