The Navigator was a massive success, so much so that it saved the Lincoln brand from extinction. When no other Lincoln model was selling the Navigator was breaking records. The first generation of the Navigator was a massive success, but it was also not without its problems (via Readers Digest).
The In-Tech V8 engine was known to have electrical issues which were expensive to fix. The suspension was an air ride, which meant the system would go out after many years. Without proper repair to the air ride suspension, the Navigator was left in an inoperable state.