Goals from Yann Kermorgant and substitute Adrian Popa gave Reading victory, leaving Wednesday with just one win in their last six games.
Kermorgant put the visitors ahead after 13 minutes, cutting in from the right and slotting the ball beyond Keiren Westwood into the far corner of the net.
Deep into stoppage time, Popa added a second, finding the unguarded net after keeper Westwood was left stranded after going up field.
Stam said: "It's been a fight and I'm very proud of my team. In these games it's going to be very tight, especially away from home and we knew it was going to be very hard. We also knew what we could do to make it hard for them.
"We scored a very good early goal and they gave us time to play. They had their chances as well, which is normal.
"Part of our game plan was to keep the ball and make them impatient. We succeeded in doing that.
"We defended, kept it very tight and didn't give them a lot of space to play.
"Ali (Al Habsi) has been very important for us. Sometimes it's the goalkeeper who makes you saves.
"We're very realistic in what we can achieve. We're up there and we're going to give it a shot so hopefully we can stay up there."