speedomeeter "bounces", o/d light blinks on and off, affects the steeing as well if speedometer "bounces" above 40 mph

just bought it , 107,000 miles, fluid lvl good looks good, maybe a little dirty. it sat for about 2 yrs i was told. found a mouse nest in it, under the bat.

Torque converters and valve bodies can't make the speedo jump. #1 - the gear on the Speed Sensor or the Speed Sensor itself may be failing. #2 - The drive gear for the governor may have worn and is allowing the sensor to skip. How does it shift? With light acceleration, it should reach Overdrive (4th gear) between 40 and 45MPH. If the shift speeds are erratic or unpredictable it's likely a governor problem. The Speed sensor can be a bear to get to. If you had a scan tool that would allow you to watch the Speed Sensor signal, you'd know in very short order.

i have a 2000 mercury sable my issue is they blown they carbon out of my car cause of a misfire on cylinder 5 the check engine light isnt on but my car cant get speed it is whinning when u first take it on the road eventually i can get speed to speed limit can it be speed sensors??

also my abs and brake light both come on while driving it at the same time brake fluid is good

Yeah its your speed sensor my mercury does the same thing. I have a 98

I have a mercury sable 1996 it just just started yesterday. My O/D off is flashing and i try to push the button off but it won't work car runs good and how can i fix it to regular Drive is it the sensor? I need help guys.