I did a carfax on a car I'm about to buy and it listed the engine as 2.5L H-4 MPI SOHC. I thought it was a DOHC. Could this be true? Isn't the SOHC the phase 2 and better?

The 98 Forester (one "r", thank you) has the 2.5L DOHC Phase I engine. It is most probable that Carfax is in error. If in doubt, you can always look at the actual engine. Also, the timing belt on this car should have been replaced at around 100,000 miles. Both the Phase I and Phase II engines are interference types.