I have one here I am working on, a nice supercab short bed, same powertrain.
He brought it to me (he's been one of my riding mower customers for several years) after someone else had put platinum plugs in it and it ran worse. I put new Motorcraft ASF42C plugs, a set of wires and a cap and rotor. It still wants to suddenly cut off and there is something in the dash that will start softly "beeping" when this happens.
Owner came Thursday and I showed him what I had done and discussed the issue with him, he said he would talk to the lady he bought it from and she if she knew or had any documentation. He brought a folder she gave him with all the ROs from 2007 on, nothing on a security system.
There are a number of blue wires spliced into the ignition primary side and I am getting a "no tach signal to EEC" code (probably explains the periodic surging and cutting off). He said he was driving on US13 when he smelled something burning and the truck cut off. he got it restarted and the beeping started then, he thought it was the key warning, but it isn't that. I have to remove the cluster face, and maybe the cluster to find what and where the module is and then just do away with it. Fortunately I have plenty of sections of EEC-IV harness sections for the remote mount TFI module.
Bill AKA "LOBO"
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"Getting old is inevitable, growing up is optional"
Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator
Wife's 2011 Flex Limited
Daily Driver 2009 Flex Limited with factory tow package
Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413