2000 windstar 3.8 engine out of balance

I have a 2000 windstar 3.8. When I start it the engine shakes violently, everything inside rattles and even the front wheels shake. Once I put it in gear and get it on the road it seems to calm down. Buddy told me bad motor mounts...changed them, bad plugs and wires...changed them... Seems like the whole motor is out of balance. It hasnt thrown any trouble codes and it is unlike anything I have ever seen... Any help would be appreciated.

Although rare the Harmonic balance pulley maybe bad.. So when in park and you rev the engine a bit does the shaking or vibration stop.??? Is the coil pack good or ever been replaced.? Sometimes you wont get a code until the coil pack goes out. Usually a flashing CEL light when this happens.. If you cant find anything else wrong you may won't to have the harmonic Balance pulley checked out.. The only ones I have seen go bad like that have been in an auto accident and the damaged body was repaired but they had a vibration do to damaged balance pulley.. But for the most part what keeps a motor from shaking it self apart is the harmonic balance pulley hub..

When I rev it up above 2000 if clears out a bit but is still there.

As garync mentioned, check the harmonic balancer. If the bolt is loose the key could have sheared making the engine out of balance and throwing the ignition timing off as the crankposition sensor gets its reference there. This has come up a couple of times on this site.
Probably best to pull balancer and thoroughly inspect.

Sounds pretty much like an issue I had a year ago. This might be of help...

http://www.automotiveforums.com/vbulletin/showthread.php?t=885567&highlight=ed_strong

let me know if you have any questions.