How do you BBQ "fall off the bone" spare ribs?

I've tried several ways, been online for suggertions, and still haven't achieved the fall off the bone tenderness. I've tried boiling, not boiling, high temp, low temp, and still nothing. Today, by suggestion, I tried to simmer them on the stove in 4 parts water, 1 part apple cider vinegar, and liquid smoke for 90 minutes. Then I BBQ'ed them at 200-225 degrees for 4 hours, turning them once. Then I BBQ'ed them in 1\4" of apple cider for 1 hour per side. Again, basteing with liquid smoke to taste. The last 1\2 hour, I put on my favorite Baby Rays sauce. I had the best tasting fat that I ever had in my life. Barely any flavor was in the meat, although the BBQ sauce helped that. But after all of that slow cooking, it wasn't close to fall off the bone. Anyone got a new suggestion/recipe to get to fall off the bone tenderness and retain the flavor in the meat? Thanks