BigE, that's great that only one 2000iQ will run your A/C at 2600'! However, as you point out, altitude will impact it. While the specifics depend on engine type (2 cycle vs 4 cycle) and carburated vs fuel injected, a rough figure is about 3% power loss per 1000 ft elevation from sea level. It isn't exactly linear at lower altitudes, but when you get up to 6000-7000 ft, it is very noticeable. For example, my 2000iQ runs my 900W microwave (that's output in the microwave; the input power is actually 1200W) just great at home at 2300'. At 7000', where the generator output loss would be around 21% or a steady-state output of about 1400W, it will run the microwave but not at its full rating, as indicated by the longer cooking time. I didn't have time to hook up and parallel my second 2000iQ the last trip, but will test it next time.
Brian