Marinate pork chops in 1/4 cup of dressing in a resealable plastic bag in refrigerator for at least 1 hour.
In a large nonstick skillet, heat oil over medium-high heat. Remove chops from marinade and season with salt and pepper. Cook chops 2 minutes per side and remove to a plate.
Add chicken broth, grapes and remaining 1/4 cup dressing to skillet. Simmer gently for 3 minutes; add chops and simmer an additional 5 minutes, until internal temperature registers 145 degrees F.
Serve chops over cooked couscous; spoon grapes and sauce from skillet over chops.