RepairPal Certified shops can diagnose and repair your 1998 Jaguar XJ8. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
based on what you said you may have done internal damage to the engine. You are going to want to have it towed to a qualified repair center and have them diagnose the problem. Do not run the motor any more as you may cause further damage to the components.