Rough Idol

When I am sitting still in My XJ the RPM's go from 500 down to 250 and it seams like it is going to die but it kickes back upto 500 or so. I relocated the vacum resovoir the other day and broke two out of three lines. I repaired the broken lines, but I am not 100% sure if they are hooked up right. Would a vacum leak cause anything like this? Anything elso you guys can think of?
87' XJ w/4.0

I had crappy idle on my '87 until I cleaned my Idle Stepper Motor.

Kenny

Where is the Idle stepper motor? Thanks

It is on the front right part of the throttle body. When you look at the front of throttle body there will be two things the throttle position senser on the right and the stepper motor on the left. The ISM will be the metallic one and the TPS will be black plastic.

Just disconnect the stepper motor connection, take out the two torx tip screws (I don't remember what size they are) and pull out the ISM. There will be an o-ring that prabably will want to stick a little so be aware of that. You might want to change the o-ring. I used brake cleaner and a tooth brush to clean it all up. For the inside of the throttle body you could use a small soft bottle brush and some more brake or carb cleaner.

When you get done if this is your problem it should idle smoother. Mine sure did.

Kenny

but wait a sec

Didn't I read here that some cleaning agents can damage the IAC? Believe someone suggested avoiding standard carb cleaner and the like. My idle's jacked up and due for a cleaning. It worked wonders last time. And that's right, I'm an idiot and can't remember what I used. Thanks for any help...