Place pork in large zip lock bag. In medium bowl, stir together beer, corn syrup, onion, jalapeno, mustard, oil, chili powder, honey, garlic and rosemary; pour over pork, seal bag and toss gently to coat pork. Refrigerate 6-24 hours.
Heat grill to medium high. Remove pork from marinade, reserving marinade for basting liquid.
Grill pork over indirect heat, away from fire, basting every 10 minutes with reserved marinade, until internal temperature reads 150-155 degrees F., about 45- minutes to 1 hour. Discard any remaining marinade; remove pork from grill and let rest 10 minutes before slicing to serve.