I'm pretty suspicious of the NIV
You have every reason to be. The interesting thing is that the translators of the NIV have revealed their agenda in their Preface.
They claim it is an "eclectic" text and their choice of readings is according to the "sound principles of textual criticism" [which in fact were proven to be very unsound by men such as Burgon, Scrivener, Hoskier, Hills, and many others]. It is simply a cover-up for the corrupt Westcott-Hort/Nestle-Aland Text.
They they also tell us that they have used some of the most corrupt documents as supplementary to their foundation -- including the writings of heretics.
Further, the NIV is based upon the translation principle of "dynamic equivalence", which means the translators have paraphrased the Bible, and a careful comparison with the KJV will show how they have not only tampered with the text but actually perverted certain truths to mean the opposite of what they really are.
Let's take just one example -- Romans 8:28.
KJV -- "...
All things work together for good to them that love God, to them who are the called according to His purpose". This teaches us that because God is sovereign, He makes all things "work together for good" to those who love Him and are called according to His purpose [the redeemed].
NIV -- "...
in all things God works for the good of those who love him". This teaches us that God becomes the worker, instead of the one who makes all things work together for good through His divine power and sovereignty.
First of all, THOSE ARE NOT THE WORDS IN THE TEXT.
Secondly, THAT IS NOT THE TRUTH THAT IS BEING TAUGHT.
Thirdly, since God allows afflictions and tribulations to come into the lives of His saints [and that is the reason for this verse being there] GOD IS NOT WORKING FOR THE GOOD IN ALL THINGS. Rather, He is making all things -- good and bad -- "work together for good". There is a difference.
So we see how the NIV changes the truths of the Bible.