I recently purchased a 99 xj and it is my first 4x4. When I got it I wanted to upgrade to 31's with a lift kit. I have been searching and I can really only afford to get a 3in lift with the add-a-leafs. Is this a horrible thing and what difference is there? I have always wanted to lift up a cherokee (this is my second one but the first with 4x4) and Im really excited to do so. Please advise

Also I took it out today and switched on the 4x4 and it stayed in part time at a low speed. I had the engine in neutral but I was not moving. To get 4x4 full time do you have to all ready be traveling at a reasonable speed and then pull the lever to 4h? Im so embarassed to sound like such a retard but I really have no clue. It made humming noise from the back.