Is it throwing any engine codes? A bit more information would be very helpful.

Xintersecty is right, if the rings are bad on #2, then the leak down test would have shown that clear as day. If it passed the leak down, the bottom end of the engine isn't causing the issue. The valves are going to be good because the leak down also verified that. That really leaves the fuel injectors and spark (plugs, wires, ignition coil, possibly crank or cam position sensor) as possible issues. Another thing to double check is the timing belt timing.