"South By Southeast" is definitely a below-average Rockford, bearing all the hallmarks of an episode churned out in an exhausted frenzy as the production season neared its end.
For the second episode in a row, Jim is mistaken for someone else, thereby launching him into a dangerous situation. Unfortunately, the reason behind the mistaken identity is particularly contrived this time around. Even worse, everything that happens to get Jim over the border (in order to get the story running) is clearly the work of a desperate scriptwriter hoping that by keeping things moving, the gargantuan plot holes don't become too obvious. Surprisingly, this is a Juanita Bartlett episode, which makes it particularly shocking -- she's usually pretty solid at plot mechanics.
Of course, Juanita's also good at character and dialogue, and there are some absorbing moments in the episode when Jim deals with a spoiled-but-sympathetic heiress. However, the rest of the cast barely registers, and everyone in this story behaves pretty stupidly pretty much all of the time. In particular, the villain of the piece has an especially dumb and transparent criminal plan he's trying to execute.
Is the end result of all this terrible? No. But "South By Southeast" only gets as far as it does on the appeal of James Garner, and a fairly good performance from Dorrie Kavanaugh. For a lesser P.I. series -- Simon & Simon, say -- this would merely be a mediocre episode. But for The Rockford Files? It's quite frankly a disappointment.