hi i'm looking for handbook or owner manual for jeep cherokee sport 1999.

An other question about the engine (6 cylinder 4.0 L)...can i change it with something more economic.

I mean can i put engine from another SUV.

 

You can find downloadable versions of the drivers handbook online.

You could put one of the four cylinder motors in, but the xj's with the four do about the same mileage as the six so you don't gain much.

 

The 4 Cylinder is just as bad as the 6, you can drop in any donor motor just remember UNIFRAME has issues and will need work if you go V8 which it sounds like you won't.
Just a question what milage are you getting I have an 88 XJ locked rear Dana 44 open front out of a 98 GC and 4 inch lift on 31's and I get 400 K's to a tank and this is normal or better than most of the guy's I wheel with some are getting 250 K's to a tank...