I have a early 99 F350. the problem started off with a check engine light, and ran real ruff while it was cold, as soon as it would get up to temp. the light would go way and would run normal. now the light is constantly on as soon as i start it, and never extinguishes. it feels like its missing, but the only codes i get when its hooked up are low boost codes. Thanks for reading and thanks for any advice.