Put some MMO in the holes for 3 days to soak ,leave open with injectors and heat shields out to purge the MMO OUT of the cylinders While cranking.(messy business without rags)Then reinstall your injectors with heat shields,Ive tried this with an old stubborn motor ,the car was sold to me as a non running car .I LATER FOUND that the compression was low and the motor was on its way out ,drove it another yr ,just not very far.If you can try a risolone product called compression repair as an oil additive this might help,to this day my mechanic who tried everything under the sun to bring this car to life refused to believe that something in a can made the difference,it pulled the compression up just enough to build a spot for combustion and the motor idled out nicely. He came back the next day as I was reving the motor and I showed him the can and he just shook his head.It was a yr almost to the day when the motor gave out ,I always regret not opening the motor by pulling the head off just to see what condition the cylinder walls were like .