Not quite. I quoted 18 verses that state the Qur'an is clear. Not some of it, but ALL of it - as in, "He explains his verses in detail". See the difference? None of those quotes so much as hint at the fact the some verses are unclear.
As to the 3 examples you gave, only one is useful. Verses 7:50-51 do not say what you quoted. Verses 75:13-19 only state that Allah will have his day of reckoning, and that your actions will be explained to you.
Verse 3:17 is the only one that supports your claim. And all it proves is that your god contradicted himself. Either the Qur'an is clear, or there are parts that aren't. The score on that is 18 - 1.
The Quran is in Arabic so translations vary which can interfere with the meaning. So often one has to refer to various translations to obtain the true gist of what the Arabic has stated. Many translators don’t include the complete meanings as there are often many so they just shorten it.
But if you look at this translation you can see that it’s going into more depth and is clearer.
There are clear verses such as mentioned below, commandments, duties, punishments and legal laws, these are all clear. But there are hidden meanings such as the chapters about the Day of Resurrection and things like mountains being folded up, too numerous to mention (if you did read the entire Quran you will know what I’m talking about) There are more cryptic verses than clear verses overall from reading the Quran.
3:7
It is He Who has sent down to you (Muhammad) the Book (this Qur'an). In it are Verses that are entirely clear, they are the foundations of the Book [and those are the Verses of Al-Ahkam (commandments, etc.), Al-Fara'id (obligatory duties) and Al-Hudud (legal laws for the punishment of thieves, adulterers, etc.)]; and others not entirely clear. So as for those in whose hearts there is a deviation (from the truth) they follow that which is not entirely clear thereof, seeking Al-Fitnah (polytheism and trials, etc.), and seeking for its hidden meanings, but none knows its hidden meanings save Allah. And those who are firmly grounded in knowledge say: "We believe in it; the whole of it (clear and unclear Verses) are from our Lord." And none receive admonition except men of understanding. (Tafsir At-Tabari).