There's your problem, if you don't have the high tech job doubler or quadruple-er then the demand for R$$$ which I-HT creates will never be balanced out as the amount of jobs I-HT supply is about a quarter the demand they create. If you want less R$$$ sims to move in, consider raising the taxes for I-HT a lot higher and de-zone some of the existing industrial and instead replace it with parks, then zone some extra Commercial parks around your city, alternatively, get the Industry doubler/ quadruple-er. You also stated that a lot of your commercial jobs are high wealth - the other alternative is to just let high wealth grow to fit the demand.