I was not aware of the fact that this same inspiration has always been a part of the Catholic church.
Not in the same way.. God doesn't just use men through "inspiration"; he also guards his Church from officially teaching doctrinal and moral error and animates Apostolic Tradition in the organic, ongoing life of the Church. Jesus said to the eleven, "Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, until the end of the age." (Mt 28:19-20)
"you" refers to the eleven, but how could Jesus be with the eleven until the close of the age? Of course, Jesus is speaking about the Church, with which he'll be with. But, how is this church composed? Is it just anyone.. or is it those who are taught and guided by the apostles? Remember, there was no New Testament then. All that Jesus had commanded these "men" was orally transmitted, and yet Jesus entrusted the salvation of the world to eleven "men" with whom Jesus said he would be with.
Is that the same inerrant guidance that led the RCC during the Middle Ages?
Yes, and the Ante-Nicean Ages, the Post-Nicean Ages, the Dark Ages, Modernity, and Post-Modernity.