Hey Flip, it could be anything from a bad electrical ground to a sensor in the transmission. Definitely something you'd want looked at by a mechanic to diagnose.
〉 Answered on Dec 12th, 2013 by Gelina Aquilina, Service Advisor / Mechanic at
It could be a wiring issue - possibly a bad ground wire for the fuel pump , something in the wiring harness is tweaking just enough when you shift gears. It could also be a sensor sending out an inaccurate reading. A diagnostic technician should be able to figure it out.
〉 Answered on Dec 12th, 2013 by Helaine Kurot, Owner/Technician at 360 Automotive
Flip, About your 2000 Navigator, If there is a check engine light on, you will need to get it checked for a diagnosis. There may be a problem with the transmission (torque converter clutch). This may or may not set a code (many times it doesn't). Another sign of TCC could be stalling instantly. A transmission shop would be able to road test your vehicle to check out your concern. Good luck!
〉 Answered on Dec 12th, 2013 by Maryann Croce, Owner at Croce’s Transmission Specialists