1993 Audi 90 CS NON-Quattro V6 - Transmission Fluid - BG A..

My automatic transmission usuall gets stuck in 2nd or 3rd gear. So I
looked at the manual and it says that transmission fluid must be
perfect and that in Quattro's you can not change the fluid. The fluid
does not appear to be low.

Two questions:

1) Does this mean I can get a transmission fluid flush and maybe help
my problem?
2) I ordered som BG ATF Cleaner. I love BG products, has anyone ever
used the ATF product to condition the ATFluid and help clean the
transmission?

I know the book says Do not Add Additives, but that was back in 1992
and my car has 165,000 miles on it and BG products have improved a lot
since the manual was printed.

Thanks

Erik