Kitchen Large Electric Appliances - Bosh dishwasher stopped doing a good job

My Bosh is about a 6 year old unit & it was cleaning dishes very well for the first couple of years, then I noticed a slight diminishing in performance. Dishes were dull and some of them were not cleaned at all. Called Sears where I bought it, luckily I also bought a service plan with it so my stupid mistake did not cost me anything. It turned out you have to “clean” your dishwasher with a special detergent like “Glisten” and so I did. Afterwards performance returned to normal until my kids loaded the dishwasher with all bunch of fish bones on the plates and that clogged up the air break up on top of the sink and that resulted in the same kind of symptoms, but after cleaning that up all was back to normal again. Since then I am regularly, about every two month use the Glisten and watch for that air break. Recently I noticed that regardless of the cycle I use ( my wife thinks that power wash cleans better, it doesn’t) , dishes have a little haze (I do use Jetdry on regular basis) and some of them have still dirt on them. So I ran a double cycle of Glisten in my Bosh and still getting same results. Any ideas what could this be and what can I do to resolve this problem? I’d hate to have to buy a new dishwasher when this one is running fine, just not doing its job well.
I have a water softener up the stream and using Diamond Brite or Kirkland Liquid Detergent ~ 1/3 to ½ tray filled.
Thanks a for your suggestions,