Need help code 42 1991 Surburban R1500 5.7

I did a tune up and crossed a couple wires and moved it out of time. When fixing the issues I was setting the timing and unplugged,one at a time, the 2 sets of wires coming out of the back of the distributor when I couldn’t find the black tan one. I found the tan and black later when adjusting. Afterwards I got a code 42. I replaced the distributor and timed it and still have the code 42. It runs strong but smells ritch and isn’t 100% like before. How do I fix? Thanks