If God intervened any time I was about to sin, and thus made it so that I could never sin, do you believe this would be contrary to the notion of free will, since it is removes the option to choose to sin (or more specifically takes away the need to choose not to)?
For example, if God kept intervening uninvited and thwarting your will, then that would be contrary to the notion of free will.
However, a very different scenario would be where you prayed to God and asked Him to intervene and stop you sinning. In that case God would be helping you, despite your temptations to the contrary, to do what you really want. Therefore, in that scenario, God is actually enhancing your free will be helping you in your stated goal to be free of something that is binding or enslaving you.
A simple analogy might explain this better. My second child was born with a severe, and ultimately fatal, handicap and her doctors told us that there was a 25% risk that any subsequent children would have the same condition. Therefore I made the decision to get a vasectomy. In this case the surgeon was not interfering with my free will - he was acting at my request.
But imagine I lived in a totalitarian atheist regime where they wanted to impose a limit on the number of children born, and where I was forced to have a vasectomy. In that case the surgeon would be interfering with my free will, since I had not requested him to perform the operation.