Electrical

I recently got a 1989 toyota corrolla dx. Automatic. It has about 140thousand mi. It was parked for about 4 yrs. And did not run when I got it. As soon as I installed a new battery it started right up. After about a week of driving, one day all the electical slowly went out comletely and the car died and wouldn't start. The next day the car started withought a jump or anything. I had this problem a few more times, each time it got worse and it had to be jump started. I thought it was the alternator so I got a new one from the junk yard. The car ran fine for a few more days, but then had the same problem again. I had both alternators checked. Schucks said they were both bad. I took one of the alternators to a specialist to have it rebuilt and they tested it and took it apart and said it was brand new and was fine. I took my car in, they looked at it, after a while they came to the conclusion that my battery was bad so I exchanged it for a brand new one. Schucks tested the battery on 2 machines and said it was 100% but they gave me a new one any way. After installing it, my car started with no problems and ran great for about a week. The other day I drove from Oregon to Tacoma and about half way there my car slowly lost all electrical power but the car still drove for a few more miles then died. After about 10 min it started back up and everything worked again. But once again. As I kept driving it lost power and slowly died. It did this about 7 more times on the way there. Each time I had to wait longer for it to start again. Several people looked at it I get many different answers but no one really knows. Any ideas? Thank you so much for your time.