Hi Cathy-- I'm assuming this is white grout with the small grout lines? If so, once dry, any tub and tile caulk from a hardware store should be fine. If not, the best bet would be to find out where your GC got the grout, and get the caulk from the same place, the same manufacturer, and the same color and texture as the grout (by texture, I mean sanded or unsanded) so that it'll match. As for what you saw when you washed it, if you hadn't added that part to your post, that wouldn't been my first step for you, just so that you WOULD get all that black crap out of there. You might even give it another shot just to make sure you've gotten it all, because that's one of the reasons why new caulking will turn so crappy so quickly sometimes. Once you've given it another shot and feel confident you got all the garbage out, let it dry for a few days, and then caulk it. That should be the end of your problems.

It's going to depend on the door. You are going to want to cut the stucco back enough each side and top if the door has a nailing flange to fasten into the trimmer/jack studs as well as on the header. The void can be filled with foam,(low expanding foam for doors and windows), befoe your trim is installed. The trim itself should be back caulked as well as topically caulked after it is installed. I would prime the trim all 4 sides before installing. If the door has no flange, you can cut the stucco tight, install the door, foam the gap, then the primered, back cualked, topical caulked trim. I dont normally recommend relying on caulk to keep water out, but seems like the only re-course without disturbing the stucco and trimming over. The bulletproof way would be to knock the stucco back wide enough to run a head flashing over stucco mould that would trim out the doors exterior. The flashing would run over the moulding. Then self adhering bitumen type flashing installs up the sides with a piece then installed over the header flaashing. Then mesh wire/weep screed at the base followed by your stucco patching.Your scratch coat can be followed by the brown coat after 24 hrs and then let set a couple of weeks before the color coat. Your brown coat will be leveled with the existing wall surface. Grind enough of the existing top coat around the perimeter to be able to feather the new top coat into the existing. Depending on wether you have a textured top coat existing, or fairly smooth, i typically have exterior acrylic latex paint matched up to the color coat and paint the new color coat area as it is usually hard to match up existing color coats that have been on the home even if you knew the product brand that was used. That way you dont have to mess with trying to match up the color coat old vs. new. You would want an exterior flat paint.

We're in the Phoenix area (Glendale, actually). The mortar appears to have some fiberglas reinforcing in it and there is a chicken-wire facing on top of the base styrofoam. I'll probably clean it up and expose more chicken-wire before repairing to anchor the patch better. Obviously, I'll be repanting the patch when it's cured enough. I'm mostly concerned with matching the texture so it blends in well.

One of the best paintable, long lasting caulks is Elastomeric/acrylic blend. The Dynaflex 230 is my favorite. You can also choose colors from Novaguard (novaflex). Michael