Is the text Quran (Mushaf) 100% preserved?
Salam,
Those who follow the holy Quran should not follow the Quran blindly as well. Dr Rashad Khalifa first claimed 2 false verses were injected in the Quran based on his careful research. There is a great deal of controversy about the authenticity of the holy Quran which most of the Muslims (even most of the Quran aloners) do not aware about it. God says,
[The Quran 17:36] You shall not accept any information, unless you verify it for yourself. I have given you the hearing, the eyesight, and the brain, and you are responsible for using them.

The Quran
Notice here, God does not say, you shall accept all information in the Quran without verification.
If 2 verses are false how can you be sure that the rest of the Quran is not corrupted at any extent?! No, it is not so easy to verify by using any magic number or whatsoever.
That’s why God does not say we need to follow the Quran to be saved from hellfire. Definitely Quran is an additional blessing from God, if we follow it we will surely be successful both here and hereafter. Anyway, minimum requirements to be saved are:
[2:62] Surely, those who believe, those who are Jewish, the Christians, and the converts; anyone who (1) believes in GOD, and (2) believes in the Last Day, and (3) leads a righteous life, will receive their recompense from their Lord. They have nothing to fear, nor will they grieve.
[5:69] Surely, those who believe, those who are Jewish, the converts, and the Christians; any of them who (1) believe in GOD and (2) believe in the Last Day, and (3) lead a righteous life, have nothing to fear, nor will they grieve.
There are great controversies about the preservation of the Quran. Please read it. It is written by a non-Muslim scholar. Therefore, we should be careful to assess it. However, all the arguments are not silly for sure. To my judgment, it is an article contains both truth and falsehood. Corruption of the Qur’an
http://wikiislam.net/wiki/Corruption_of_the_Qur%27an
Also, it will be a good start to read an interesting article. Which Qur’an?
www.free-minds.org/which-quran
The Quran has several versions itself proves that Quran is not 100% preserved as most of the blind believers believe. God preserves His original Quran which is in Lawhe-Mahfuz. No devil from human or jinn can change that original Quran. Let us discuss this vital topic and share your honest thoughts. God bless. Your brother in Islam.
Musa Ali, 2008.