Guys, this is my first time ever posting to a forum. Straight to the point though, my motor blew and I wound up replacing it with a used motor from a junkyard. Just a quick rundown of what information I have: 2002 Ford Expedition XLT, 4.6 engine Here is a short list of things we have done leading up to this problem Replacement motor came out of a 2001 Ford Crown Victoria, 4.6 engine. Coil packs replaced Heater core blown out with air hose Catalytic converters replaced New muffler added A brief description of the problem: When started, my vehicle does not smoke and it does not miss while in park. It does however have a small tick to it that has been identified as a lifter. When the vehicle is put into drive, it starts acting like a coil pack is bad and as my Dad described it, having a bumblebee in the muffler. He also says it acts like it has lost half of its power, but when it gets up to about 65MPH, it evens out. Guys, any help with what this could be would be greatly appreciated. I have been told that it's possible that the computer on my vehicle needs to be reprogrammed with the current motor, but that's all we know at this time.