I have to guess the last owner of my truck was trying to get better mileage since there was one of the wrong injectors in it when pulled the radiator i found what I think is the right big block...

I was having a hell of a time finding real 454 injectors almost everywhere I looked has 350 and 454 as the same part number

my thermostat was upside down ran hot when I pulled up one hills in flagstaff till the fan started pumping I could bet on it staying in open closed loop check your vacuum at idle and timing I swear...