1996 mercury sable 3. liter engine dual cam had tune up and car still running rough..was told i needed a new computer. a new computer was installed. it solve the problem, but created a new one. the transmission will not shift properly, or go over 35 to 40 miles an hour. won't shift gears. put old computer back in car..runs rough again, but transmission back to normal. the numbers on the new reburbished computer all match. Need new computer to make AC work and run good, yet transmission won't work with it. I am a woman, and cannot spend another penny on mechanics "guessing". HELP!!!

USA car? yes/no? lost spark did you>? or DTC p03xx errors>?
that sensor is called CKP, and on cars engines it can be many places, some even oddly places, it is not the cam sensor CMP
the 2003 , 3.0 liter V6

the manual covers this.
https://eautorepair.net/Marketing/Default.asp

i will show a photo of it mounted, just using google . (brave)

some times just pretend to buy the part at the dealer, Merc
and see where it is , at ford.com
the dealer says it also fits Ford Mustang 1996 - 2014
that fact makes it more easy.
oooooohooooooo , there are 2 engines that year,
2 valve and 4 valve per cyclinder, oops not told shown in the service manual
2V
The crankshaft position (CKP) sensor:

• is a variable reluctance sensor.
• is mounted on the engine front cover.
• is triggered by a 36-minus-1 tooth trigger wheel located on the crankshaft pulley and damper.
• provides base timing and crankshaft speed (rpm) to the powertrain control module (PCM).

4V, ok , luck you its the same but not CMP

Then you did not fix the problem. Codes are not cut and dry, it can be the part the wiring to it or in rare cases a defective Powertrain control module (PCM)

Rough idling can be caused be `ye olde vacuume leake'.HaHa!
So check for THAT first.I have also seen those cars eat a set of spark plugs and wiring pretty fast, so remove a coupla' plugs(they're easy to get to if engine's cold)and check their condition. (:^) don-ohio

Hello Loren.
There are two different engines on the Sable that year. Both 3.0 liters but one has a dual overhead cam engine.
I'll go with the more common single overhead engine.
Squeeze the tabs to remove the ignition cables from the top of the coil. It would be a good idea to mark which one goes where first.
Then undo the capacitor connector. Undo the four retainer screws.
Reverse to reinstall.
Apply a film of di-electric grease to the coil towers before you put on the coil wires.

If yours is the dual overhead cam, let me know here in comments and i will give you directions.

Thank you for using FixYa.
KL

you got a miss in the ign. system do a full tune-up, wires, plugs and filters

change the spark plugs, wires, and air filter and maybe the gas filter if needed in order to do a 'tune up' on a 1996 Mercury Sable.

If you are looking for the powertrain control module (PCM) it is located in the right rear corner of engine compartment ( Passenger side), mounted in Firewall

hi im wes if you have a 3.0 litre dual over head cam it ts behind the timing belt. if you have a 3.0 litre pushrod engine its on the front of engine any help pleas rate me trying to make a buck thanks wes

Mercury had a recall on 3.0 duratech motors in 2000 and 2001. If you get a fuel smell at startup then you might have a bad lower intake gasket, it could cause a miss if seal is cracked. Article No. 01-4-3 you can get it on AllData.

Also, check the PC rubber L piece that runs from the PVC valve to under the throttle control - it could be busted.

Make sure ignition wires are not cracked. If you haven't tuned it up in over 30-40K consider doing that.

try new plugs and wires and some fuel injector cleaner should make a big difference