I think it would be enough time in either airport. Timing is probably more of an issue at CDG since no AA flights depart after 2pm.

At CDG coming in on IB, you'll be in 2D. You then leave security, walk underground and come up in 2A for AA flights. Here the lines can be long depending on the time of day. AA has departures to CDG, JFK and MIA all around the same time, late morning, so it can be a zoo. But still, as long as bags are checked through, 2 hours would be enough.

And at LHR, the same. IB would come in to Terminal 2, you have to take a bus, collect AA boarding passes at FCC and pass security again but can easily be done in 2 hours.

I'm interested to hear others say you can check bags through even when on separate tickets. I tried this once going BA to AA and it worked, but I thought it was really a once-in-a-lifetime thing. Maybe not??