Does the Bible contain the elements of Christ's gospel necessary for salvation? Absolutely. You can find all of the elements of Christ's gospel in the Bible. The Bible is materially sufficient.
However, it is not always formally sufficient -- given in a form that is easy for the average reader to fully comprehend the gospel. Because it contains Christ's gospel, it has the ability to save those whose hearts are open, who ask of God, and who test everything by scripture.
There is tremendous disagreement, even among evangelical pastors, about how people are saved. The elements of Christ gospel are not always clear to many Christian believers. For instance, many evangelical pastors continue to disagree as to whether faith, repentance and surrender are all necessary for salvation. There is a welter of confusion among evangelical teachers about these issues.
As believers in Christ's restored gospel, we frequently say that "plain and precious truths" were removed from the gospel. Many evangelical leaders immediately assume that we are referring to actual text that was removed from the Bible. That is not always the case. The text can be the same, but the way that the Bible is taught can vary widely from one teacher to another.
When evangelical churches limit the function of interpreting scripture to a single personality or pastor, it is entirely possible for important parts of Christ's gospel to be misinterpreted and in effect removed. For example,
I Peter 3:21 tells us that "baptism doth also now save us." By ignoring this passage, well meaning evangelical teachers mistakenly maintain that water baptism is unnecessary for salvation. Many evangelical pastors have honestly but mistakenly mislead congregations who are depending on their pastors to interpret the Bible. A precious truth has been removed from the many different evangelical gospels that exist.
Though they all work from similar bibles, evangelical teachers have arrived at different conclusions about doctrines of salvation (i.e. what theologians call soteriology). It is the responsibility of the priesthood of all believers to ask God directly for guidance on such issues and test what they receive by scripture. This responsibility cannot be delegated to a single person who interprets for the entire body of Christ.
The Bible is materially sufficient in that the basic elements of Christ's gospel can all be found there, but Christ's gospel is not always stated in a way that is absolutely clear to the majority of Christian believers. As a result, there is a great deal of confusion among Evangelicals about the gospel of Christ.