[THEFERMANATOR]

I've never changed one, but quite a few people have done it before. When you unplugged the optical filter harness, did you remove the filter and then recconect the plug that did plug into the filter back into the optic? If you didn't, try it. GM released a bulletin in 97 saying that the optical filter was not required. The main reason that it was installed in the first place was to clear up the AM radio reception. If you didn't plug it in, then your pump is running on base timing(roughly 3.5 degrees) and will not advance. It will also limit your fuel supply as well.