According to grammar books, when you are refereeing to a general past ability, you can use both “could” and “was/were able to”, but when the reference is to a single occasion in the past, only “was/were able to”,“managed to”, or “succeeded in” should be used. But while I was listening to an audible book, “English Grammar Boot Camp”by professor Ann Curzan, I heard her say “ and I could find it” in the following context.
“Off of”tends to be colloquial, but it will sometimes appear in more formal writing. I went and searched in the Corpus of contemporary American English and I could find it in academic prose…….
As far as I know you should say: I ran after the bus and was able to catch it, not [ and I could catch it].
Shouldn’t Professor Ann Curzan have said “…and I was able to find it?