We have been grilling for years on a Webber, why does this grill keep flaming up and burning everything?

As with all grills they all have their own cooking nuances and getting the best performance is learned through experience. It sounds like you may need to turn the heat down or even turn a burner off to keep from overcooking your food. For example you want a very hot grill surface to sear a steak and after searing the steak it is moved to a cooler part of the grill to finish cooking. Try this and it should help your over-cooking issue.