As others have said, this will be a challenge. Making transfers within CDG2 takes nearly an hour, even with access to priority security. Coming in from CDG1 will be even more difficult. I agree with the advice to rebook to a later connection if possible; I would leave at least two and a half hours.
You will need to clear immigration as quickly as possible -- with luck, there will be no other flights arriving in the satellite where US comes in at the same time. Then you will hightail it to CDGVal, which is the automatic shuttle that runs between CDG1 and CDG2. That takes about 10 mins. You will then need to walk to whatever part of CDG2 where your flight to FCO leaves and clear security. (I think Schengen flights on AF these days are all in 2F, which is another 5-10 minute walk from the CDGVal stop.)
You might make the connection if you are in C on your AF flight and do not check bags (note that AF has a stricter weight limit for cabin baggage than US does). That way you can take advantage of priority security at CDG (called "Accès no. 1"). You should also check in on line before your flight; US will not be able to check you in for your AF flight, and you may not make it to CDG2 in time to beat the checkin deadline.
If you are in Y on AF, you will probably need to check bags, because AF allows only one carryon in Y. If you check your bags from the US, you will not need to collect them at CDG, but I'd be surprised if the bags make the connection.