It is always best to fix your shift linkage before it gets too sloppy. The three areas of the linkage that need periodic service are the shifter base, the box under the shifter and the linkage parts back at the transmission.
* Shifter base - When plastic pieces break in the base of the shifter, the shifter will usually drop down and develop up and down play causing difficulty in finding gears and finding the correct shift pattern. The base is a bit of a rubrik's cube. Remove the shift boot in order to access the 2 bolts that secure the shifter base to the floor. Remove these two bolts and then the through bolt that connects the shifter to the shift linkage. Now you can take the shifter out of the van and work on a bench to disassemble the base and reassemble with new plastic parts and grease it up good.
* Shifter box - If you have real scratchy shifting instead of smooth as butter shifting, it is often because dirt has gotten up into the shift box. Lower the spare tire clam shell and spare tire for access. Clean out all dirt from the inside of the box. Apply grease to the rails on the inner sides of the box. The shift rod that travels to the back has plastic caps on the arms that come off the rod that come in contact with these rails. Without lubrication the plastic gets ground away. Unfortunately the plastic caps are not available separate from the rod so you try to keep this area well lubricated to protect them so you will not eventually have to replace the rod.
* Linkage parts - Back at the transmission, play can develop in a number of areas. There is a shift lever on the side of the transmission shaped like an upside down U with a plastic ball on the end. The ball sets in a cup that is attached to the shift rod with a roll pin. The rubber boot wears with age causing the lubrication to dry up, allowing dirt to get into the ball and cup, causing both the ball and the cup to wear. The roll pin will also sometimes wear, allowing slop in that connection too. Replacing these worn parts, applying lubrication and installing new boots to protect these areas will make this area as good as new. There is also a bushing at the center of the shift linkage located right behind the gas tank that is also wise to grease.
Once these areas are addressed, you may need to do a fine adjustment to the shift linkage by loosening the two bolts at the base of the shifter and moving it until the shift pattern is found with ease. If all gears cannot be found in their correct locations, it may be necessary to loosen a clamp in the middle of the shift linkage so that the two linkage rods can be rotated a spline or two in order to get the shifting into a range that the fine adjustment can remedy.