I have a 87' F150 with the 3 speed automatic
Every morning when I back out of my drive way, I put her in D and have to wait usually 30 seconds to 1 minute before it kicks into drive, whats up with that?

 

Maybe needs a fluid/filter change. I had an old F250 that used to do that, and the fluid/filter change took care of it. Check fluid level as well.

 

does it actually kick or does it slowly feel more and more "in gear"? Does this problem go away after the truck has been running and only happens after extended sits.

 

guessing fluid level. might have better chances posting in the correct section for year of truck

 

I have had the fluid replaced, but not the filter. It kicks in all of the sudden. Its only a problem after its been sitting about 8 hours

 

Sounds like low fluid level, or perhaps a clogged filter to me. You said the fluid was replaced, but there may be a leak in the system somewhere. First thing I would do is verify the fluid level. To check properly: Drive the truck for at least 15 minutes to get the tranny nice and warmed up then park on a level spot with the truck running. Slowly shift through the whole range and back (i.e. P, R, N, D, 2, 1, 2, D, N, R, P) allowing a second or two in each shifter position to fully engage. Keep it running in park, then check the tranny fluid dipstick a couple times to ensure a consistent reading. If you are low, there's your problem. If you are at or near the full mark, than you may have a clogged filter or other problems.

I had the same problem with the C6 in my '73. It would sometimes take a few seconds to engage in gear when it was dead cold. Then worked fine after. It turned out to be a slow leak from the transmission pan gasket. I replaced the fluid, gasket, and filter and haven't had any problems since. Also make sure you have the proper type of ATF fluid in there. Earlier C6s used Type F or FA fluid whereas later ones used Mercon V.