recently purchased a 97 bonneville and a few days later the check engine light came on. The code that came up said it needed a new shift cylinode. Got those replaced but now tranny is slipping a little. Just would like some opinions. Is the trans slipping just normal wear or could the mechanic who fixed the cylinodes cause the new problem??

1. bring it back to the shop that did the work and tell that whats happening before you do anything