What is the procedure for self-transfer at CDG?
I will arrive from Dallas at CDG terminal 2 A on American at 1:25 p.m. I booked a separate ticket on Air France departing for Clermont-Ferrand from terminal 2G at 5:30 p.m. How complicated is it if I check a bag? I know I will have to pick-up the checked bag to clear customs and then recheck to Clermont-Ferrand. I'm assuming I will have through security and check-in for the second flight.
May find some useful info here
https://www.parisaeroport.fr/en/passengers/flights/connecting-flights
With 4 hours between flights, you have sufficient time, even if there is one of the major delays at immigration control, for which CDG is infamous. Once you exit customs, which takes no time itself, you can walk across to terminal 2G, check in your luggage, security, then to your departure gate.
It should be very straightforward.
If everything goes as planned i.e. the plane is not late etc, you will be fine. Always a risk when you plan two separate tickets this close together. We once had a plane come in 5 hours late from the US but that was unusual. Your second flight is a domestic flight; check in probably closes 40 minutes or so before the flight (check that) but with the time you have if things go as usual you are fine. Just get your head framed to roll with the unusual if it happens.
2G is only reached by bus from 2F so you first have to get from 2A to 2F. You have plenty of time to do so.