I got this set on Amazon which according to Rock Auto is the correct part umber for 99.5 f350 crew cab.
I have to SLAM the door SO hard it's maddening. It's been 3 days - no change.
Is this the right part?

 

You might be able to adjust door striker peg out a little to ease the pressure.

 

That would be my thought as well. Could be that the new seal is so much thicker that the original it is requiring more pressure to let the door latch.
You sure there isn't something in the way that is stopping the door from closing normally?

 

Oh I'm sure. I expected this somewhat from reading other threads but I have to use both hands and SLAM the door shut. When pulling the interior door handle the door pops open like it's under a lot of pressure.

So is the part for 1999 the same as 2003?

 

I checked the Amazon you posted and there was a CHECK FIT button and it does NOT list for the 99. XLT or Lariat (mine)
I would be willing to bet that is the issue.

Rock auto shows this for your truck...
FAIRCHILD KF3043 {#3C3Z2520708AA}
That is for both sides. $47.79

Shows this one... $55.05

 

I got the Fairchild kit for my super cab to fix a water leak on the passenger side. I need to do my drivers side now because I can see light between the doors. I do have to close them with some authority, but they seal good and they are nice and tight.