The Rockford Files is an all time personal favorite, the best TV Series ever produced (a solid 10).
Out of 119, The Rockford Files episodes, 118 of them could literally be modernized & successfully repackaged today, as a detective series, by merely updating decor & perhaps swapping out some stock-footage of dated automobiles (going back 4 decades), and that was how far ahead of its time -it was...
The ONLY episode that arguably comes close, to something being a miss & not hitting on all 8 cylinders, surfaced in Season 4 Episode 15 {January 13, 1978} : 'The Gang at Don's Drive-in'...
Granted, there's different strokes for different folks, and the uniqueness of so many different (guest) actors, coupled w a (diverse) plot each week, was all part of the recipe that, appealed to such a large fanbase & was responsible for making this Television Series, an All Time Favorite!
But this insight being stated, the referenced ingredients that made, for such a will kept secretive recipe, were seemingly devoid in the production of the 15th episode in the fourth season: 'The Gang at Don's Drive-in'...
Not missing in this particular episode, is the exceptional acting that, James Garner & the Cherokee 'gang' always brought to the table, nor was it an issue w any of the guest actors. But, there was something obviously a miss, in this one episode that, separates it from the other virtually flawless (118) episodes.