CHM

I've had a rough idle and miss for several months on my '91 with 140K on the clock. I was told it was injector #1, and proceeded to perform the on-car checks. I disconnected the harnesses from 1,3,4,5,6 (2 is impossible without taking the whole thing apart) and noted the severe degree of corrosion as well as the brittleness of the harnesses. I could not even measure any resistance on the 1 and 3 injectors before I cleaned the contacts. After cleaning the contacts, I get about 10 ohms on 3,4,5,6, but around 70-80 ohms on cylinder 1. So, is 1 functioning at all? The car runs a hell of a lot better since I cleaned the contacts and repaired the harnesses, but do I need to replace the #1 injector? Any other suggestions? I'm new to the injector work. I also need sources for new injectors since the dealer wants about $125 each.
If I do the work, any hints when removing the intake manifold? Thanks.