Help. I have a 90 with 132k on the clock. She doesnt have any mods yet but I have done the plugs and wires recently and added new SC oil. Even before I did the wires I had a vibe or better yet a small rumble that starts at 2000 rpms and stays the same throughout the powerband. I expected it to go away after I did the plugs but it didnt. My power seems to be ok but I cant seem to find the source of this vibe. Someone please help.