"When I found... " the verb "found" is in the past tense. This requires the past tense to follow.
When I found the Master's degree program, I knew that it was the one that I wanted to pursue.
Contrex, please stop filling ESLs head with nonsense about English. There is nothing in the English language that "requires" that we maintain the same tense throughout a sentence.
We certainly have the option to use a backshift as we report but as you've noted, it does not mean that the pursuing has ended.
When I found the Master's degree program, I knew, it is the one that I want to pursue.
This is certainly possible, in fact it happens all the time.
Jinmin, the normal neutral situation is to backshift. This is probably what has misled prescriptivists to think that language always works this way. This actually is a common theme for prescriptivists, a failure to look carefully at how language works.