I have a 1999 mercury cougar V6 (auto) car trouble ?

[alfonso]

Ok when i stop it vibrates unless i put it on neutral then it stops also sometimes when I floor it eighter while iam driveing or when I stop and then floor it it takes its sweet time to accelerate like it gets Stuck at max rpms for a bit then ill hear a small pop then slowly it will pick up also when iam going to stop it wants to go and when I shift it to neutral the rpms goes all the up on it own why are the causes for all of these problems??? I also have another cougar 99 with 125xxxmiles (stick) but gives me no problems and this coguar 112xxx miles (auto) is idk thanks for the help