My 89 gt is doing the same thing and i cant figure it out i have changed every thing ignition module,wires plugs,cap,rotor,act. sensor , fuel filter,coil, and i checked fuel pressure and its fine, so i took the ignition module and had it checked and it was bad, so i put a new one on it and it ran good for about a half an hour thin done the samed thing again , had the ign. module checked again and it was bad so for some reason it keeps burning up modules, any body know what it could be please let me know!!  

Had the same prob with my 1991. check the harness wires!!! Good luck  

Had the same thing happen to me twice on my 81.  Try checkin the voltage regulator. See how your charging systems working, if its putting out to much juice, I think it could fry it.  Also what size pulley are you running on the alternator?  

Also check your slide on your column. Your key actuates a slide. Maybe somethings come loose.  

my cpu keept saying bad pick up 4 distributers later and i couldnt go over 2500 rpm when i put my foot in it it fell flat fule presure read little low come to find out it was a pluged full pump other ting is if you have a ground issue to run extra grounds off the cpu back to the bat i called ford tech line one day and talked to a tech who says he helped build the mass air conversion harness for ford racing he told me to run 2 or 3 ground wire from the main ground pins on the cpu harness. the different systems sometimes gets corosin but by running a wire from each ground pin in the cpu harness it would eliminate any and all ground issues in the entire system. so ypu dont have to try to find it but if its a short thats different. i dont know if this helps?  

I now have changed the harness to the computer with a new ignition module so i know it is not a short in the harness ive also ran more grounds and changed the computer and also changed the altenator and its pigtail and still have the same problem im running out of things to check hope someone has some ideas. PLEASE HELP!!!!!!!