The definition of P1309 is: Misfire monitor hardware - CMP misaligned, CKP/CMP noise, PCM AICE chip. Expanded definition: "There is a problem with the hardware (wires, sensors, engine computer) which is involved in detecting misfire. The hardware problem could be a misaligned CMP (CaMshaft Position sensor), or CKP (CranKshaft Position sensor) or CMP sensor noise (“static”), or a chip inside the engine computer."
http://wiki.answers.com/Q/How_to_fix_or_trouble_code_p1309_on_1998_Ford_Taurus Connect backprobes of digital electrical multimeter (“voltmeter”) to engine computer (PCM) pins 58 and 103. Idle engine and watch the voltage signal from the CMP vary from 2 to 8 volts.
http://74.125.47.132/search?q=cache:wv9VZLaLJ2YJ:wiki.answers.com/Q/What_does_inspection_code_p1309_means+P1309&cd=3&hl=en&ct=clnk&gl=us&client=firefox-a Check the CMP wires, from the CMP to the engine computer for shield (wire foil covering) for ground. The shield should be grounded. Where the wires connect to the CMP, spray a cleaner in that area to blast away oil and gunk. Disconnect the connector at the CMP and check the connector for damage, gunk, and that rubber piece that should be around the pins.
If someone has had the CMP out, they may have put it back in incorrectly (out of “synchronisation”). You’ll need the repair manual, and the tool for setting the camshaft position sensor (the synchronizor). A new synchronisor comes with the tool, or you can borrow it, or get it from ebay (about $35). The CMP shaft may be worn, which could cause an irregular voltage signal. http://74.125.47.132/search?q=cache:rStPfhYaPVsJ:fordforum.com/forum/showthread.php%3Ft%3D7900+ford+aice+chip&cd=4&hl=en&ct=clnk&gl=us&client=firefox-a
Replacing the camshaft position sensor, using the synhronisor tool to correctly align it, may be your fix.