Hey guys I just got done pulling the engine and putting a new one in. I have a 99 mustang 3.8 in it and replaced it with a 01 3.8. took it for a short drive around town and everything seemed fine. but once i got on the high way i realized that once the car gets to a little over 2,000 rpms it has this vibration. Its not shaking the hole car or anything but you can deff feel theres a vibration. Hope to get this salved. Any help would be great thanks everyone.