Wont start anymore

1987 Chevy Celebrity, 2.8 FI. Car was the most trustworthy car ever. Its started cutting out when it would reach operating temp and would not restart till it cooled off. Problem got worse and now it wont start at all. I changed the CPS and ICM. I checked fuel pressure at start and at problem and it 40-45 so that should eliminate the pump or filter. Its an old car and a lot of wiring is greasy and hard to ID. I poured my heart and soul into this car doing heavy body mods but at no time altered any electric or mech operations to the car. Just body mods, and yes, I did disconnected the battery during welding. The car ran after the mods and made 2 car shows before breaking my heart. This may be helpful. During welding there was a small fire under the dash and it was put out quick and all wiring was checked for burns and all were fine but, it was near the ECM so could it have fried the ECM and/or Prom with the heat?