corvette95

Check Engine Light keeps coming up at random on my 96. Its OBD2 and I think the code was 0400 but was sure it was egr failure. I also getting mild misfire cylinder 1. Replaced injector at cyl 1 , cureed misfire. New pcv valve and cleaned thottle body and did a visual inspection of emission lines including rear charcoal tank. Didnt have a helper to see if egr was moving or not. Book says remove PLENUM to access egr wiring harness? Is this needed or can someone offer a better starting point?