1992 Subaru Loyale sedan

I’m having trouble with figuring out what is wrong with this old girl. I bought her a year ago from a man claiming to be a mechanic, I’ve called him when ever something went wrong. After a few months the darn thing would need to be jumped every so often leaving me stranded. The battery had been tested and was told it was good. Then 3 months ago, my husband stared to accelerate and the power cut completely. Luckily we were right nex t to an autozone. The car would not jump start at all, we had to tow it . We tested the battery, starter and alternates. To them everything was ok, the alternator is worn but was told that it couldn’t be the cause. The battery is from 2012 (was told it was new) but again told it was fine. Now when we try to start her the hear the fuel pump click and and odd buzzing from the block, the gauge for the battery voltage drops to 8 completely draining it. We had to change the distributor for after the ‘mechanic’ took a wrench to pry it off swearing that was the problem. It has new spark plugs, fuel filter, and an oil change on top of it. I’m tired of throwing money at her, and can’t afford a new car. Any help is appreciated.