I am wondering why my 2006 e250 superduty is swaying really bad?

The other earlier comments could be correct, but it could also be caused by faulty/failed shock absorbers or a combination of anti-sway bar bushings/links, shock absorbers, or aft center of gravity load distribution, which would take the front load off the front axle. In regards to your comment about play in wheel, with engine off, steering wheel unlocked, grab the steering wheel at twelve o'clock and violently rock it between ten and two o'clock. If you hear clunking, you have worn steering linkage parts. Then have one person rock the wheel while another looks under it to see and touch for the noise source. Also check the pitman arm for looseness. The steering gear may need adjusting. Any of these condition in combination, or all of these conditions are at the root of your linear instability issues.

You may have broke the sway bar free from its mounts. Need to check this out ASAP. The other possibility is you lost one of tie rod ends connected to the steering knuckle.

POSS SWAY BAR OR END LINK ISSUES. THE BAR HOLDERS BREAK AT TIMES OR LOOSE BOLTS

Are you carrying a lot of weight? The other comments are good, but it could even be as simple as weight distribution or even a bad alignment or uneven tire pressures. Start simple and work your way up to the conclusion. Ford vans have always tracked rather strangely. Just look at another driving down the road and tell me it dosent look like its crab-walking. Amplify this with worn suspension components or tires, and you could be having the ride of your life. Hmm... that could be an ironically good slogan for Ford.

I sued under lemon law and won for the same reason. Still have the van got 2,000 back out of 6,000 win. Go for it