I would use 10W40 in the 96 and 5W20 or 30 in the 2002.
For the 96 with sluggishness, you need to gently clean the MAF sensor wires with carb cleaner and a toothbrush. It is in the air intake tube. After cleaning, disconnect the battery for 1/2 hour, then reconnect so the computer can relearn the clean sensor. Drive for 10 miles, it will run rough until it relearns.
Section 03-14: Engine Controls, Electronic
1996 Town Car, Crown Victoria, Grand Marquis Workshop Manual
DESCRIPTION AND OPERATION
Mass Air Flow (MAF) Sensor
The mass air flow sensor (MAF sensor) (12B579):
- is mounted on the corner of the engine air cleaner (ACL) (9600).
- uses a hot wire sensing element to measure the amount of air entering the engine; air passing over the hot wire causes it to cool.
- sends out an analog voltage signal to the PCM (12A650) to determine the intake air mass. The PCM will then calculate the required fuel injector pulse width to provide the desired air/fuel ratio.
The mass air flow sensor hot wire sensing element and housing are calibrated as a unit and must be serviced as a complete assembly. Mass Air Flow (MAF) Sensor