What color sample tube did you use? If I recall, the 89-93 SC's, using a C&L 76mm MAFS would need a purple-coded sample tube for 42# injectors. Also might want to verify your injector size....some of the all-black Lucas ones could get mixed up easily.
So I did have the wrong injectors. Got the right ones in and it runs fine for a bit, but then runs like crap. I upgraded the fuel pump too. I got a code for an intake temp sensor. After I replaced it, gas started coming out the exhaust again. Any ideas?