low rpms it has its shaking sound kinda like grinding shifting

What is your question?

have a 96 Oldsmobile Achieva how low rpms it has its shaking sound sound like it's trying to engage and the over drive won't kick on when I floor the gas. Can I fix with out an expensive mechanic I've tried using seafoam and Duralube transmission cleaner all kinds of stuff even replace the four silinoids in the transmission itself Help James