If this is an automatic it sounds like the selector plate is comming lose its held by 2 screws under the shift plate cover. remove the plate shift into park do not start make sure the pin on the shifter is all the way in the selector its that big black V shaped elec.thing. Thats the selector if the screws are lose tighten them and if it seems the pin is still short you can use small washers to space it closer. Useing a magnet stick put the washers in between the selector and the bracket and push the screws back and tighten. good luck it does work.