My searches came up fruitless, so I'm hopeing someone can help.

My driver's door won't stay open if there's even the slighest incline on where I'm parked. The three other doors stay open no problem.

Is there a pin or something that keeps it open that I could be missing?

Thanks

Hmmm, not sure... here is the diagram of the door components:

http://www.realoem.com/bmw/showparts.do?model=GF83&mospid=47528&btnr=41_0013&hg=41&fg=40

perhaps the front door brake (item #2)...

+1

Here is where you can buy it, http://www.autohausaz.com/search/product.aspx?sid=val0hoifazmxnlvsvyfczcj5&makeid=800003@BMW&modelid=1303254@740I&year=1998&cid=13@Body,%20Trim%20%26%20Lighting&gid=1378@Door%20Check/Stop

I would probably take it to an independent BMW mechanic and get a quote first. I mean, you could buy the part and try to replace it yourself, but getting to the inside of the door can be very tricky.

http://www.autohausaz.com/secure/PartImages/51218150019.jpg

http://www.realoem.com/bmw/diagrams/e/v/147.png

Got mine at a junkyard for $5, took 10 minutes to replace. When you're at the junkyard, you can see how to access it for re-installation when they remove it from the donor vehicle.