1994 GMC Jimmy SLE

4wd doesnt work correctly, it clicks and clanks, and jumps forward like it is going in to 4 wheel drive but no power goes to the front, the front drive shaft even has power to it, i layed under it while my buddy inched forward and the drive shaft spins... any ideas? i would like to handle this myself if possible

 

There is a wealth of information just a search away. The Tech Article (DIY) section is a good place to start. Have a read through this, then search a bit more once you get some ideas:
4x4 No Worky.... Maybe this will help....

 

sounds like the vacuum hub actuator located under the battery on the fender.
Inspect the rubber on the unit and if it is cracked most likely thats your issue.
Also inspect and replace any bad or broken vacuum lines.

 

removed front drive shaft 2 to 2.5 years ago . had no front pull, vacuum actuator still worked , transfer case worked , front grinding when in 2 wheel . i removed drive shaft and grinding stopped. haven't really done anything since, figured i would have to drop the front axle. bought front axle and saved the gears . anyone know what to do?