Adjust or replace hinges
Sorry, there is no adjusting these style hinges, they are welded in place, you can usually make them better by replacing the pins and bushings in the hinges but if the hinge itself is wore that bad where bushings wont fix it you're looking at having a body shop weld new hinges in...
There is a sticker on the drivers door. It will tell you.
Replace door moulding
like this.... http://www.youtube.com/watch?v=SVVozUkfDO4
If the door is sagging then you could look at the door pins and bushings. If the bushing is cracked then it will sag and therefore not close properly. If that is the case then the pins and bushings should cost under $10 and take about a half hour to do. Hope this helps.
with a screwdriver
Open the drivers door and you will see a sticker on the door jam are door with that information on it.
There is a good possiblity that the hinge pins and bushings are shot causing the door to drop. This is common. You can purchase a pin and bushing kit from your local auto parts store. The only trick is removing and replacing the spring that holds the door open. You can rent or buy the tool for that job also.
All you have to do is look at the sticker on inside of the drivers door or door jam. And it will give you that infomation.
You can fix a sagging door on a 1996 Suburban by replacing the door pins and the bushings.
There is a sticker inside of the drivers door jam that will tell you that infomation.
Its on the tag on the drivers side door
Just beneath the drivers side door, behind the frame.