I agree as "I was saying..." is for when you are interrupted while in the middle of speaking and are trying to continue from where you left off. Jill : I think its supposed to rain and.. --A loud train passes by and Jill waits. -- Jill: As I was saying, its supposed to rain, so lets wait and go to the park tomorrow instead. "As I said" is used for quoting yourself. It's used to refer to something said earlier in the conversation. Jill: Its supposed to rain today, and as I said, the park is really no fun when its raining. Sometimes people will say, "...like (I/he/Joe) said,..." to quote themselves and others. Its more casual, though.

Hi Fan, It depends on the context. However, "As I was saying" can be used if you were interrupted ("As I was saying/trying to say before John butted in..."), whereas "As I said" means you're going to repeat something that you mentioned earlier ("As I said, it's very difficult to find a good job at the moment"). In some contexts, though, they can mean the same thing ("As I was saying/As I said, you can't just walk into his office."). Hope this helps!