It may your air ride system. Try converting the car. Go to Strutmasters.com and see if they can help. They helped me with my 2003 Lincoln Navigator problems, I'm sure they have something for you :)
1998 Navigator air suspension switch is located in the right front passenger compartment. Its by the right front passenger's right foot under the dash. You may have to stick your head up in there to see it, but it is marked.
It is in the right front corner of the engine compartment (passenger side)
Turn OFF the air suspension switch that is located in the right front passenger footwell , by the kick panel
I believe it is in the right front passenger footwell , by the kick panel , on a 2000 Lincoln Navigator
Only one air compressor is used on a 2003 Licoln Navigator and it is located on the front right hand side of the engine compartment
If your navigator has air suspension then the switch located in the rear driver side panel where the air suspension switch is...it is right below the suspension switch. hope that helps.
The front relay is on the passenger side kind of hidden but you'll find it on the upper front right side on the passenger side.
Under the dash on the passenger side to the right of the glove box is a air suspension and fuel cut of switch. It will say which button each is for.
Possible bad front end part.
On the right side of the front passenger side foot well
Yes it does....it uses this relay to control the air suspension. It's located behind the front bumper on the right hand side. It's black in color and has an aluminum heatsink with fins.
check your front suspension spring