From the looks of it I would say you have a good airplane on your hands but just need a few minor "tweaks" to get it going. I have flown half a dozen Top Flite .60 size Corsairs with everything from a .61 two stroke to a 1.20 four stroke and anywhere from 9 1/2 to over 13 pounds. They all flew just fine. If yours is somewhere between 9 and 10 pounds then, as noted by Dave above, yours is on the light side of the spectrum! At that weight they are real sweethearts assuming that you've built it straight and true. And the .91 ought to pull it around like a Rocket. I flew my 65 inch wing span, 11 3/4 pound Hellcat with the OS .91FX and it was radar gunned at over 100mph. It it's running right, and you've got a suitable prop on it, there will be absolutely no problem with it pulling around a 10 pound Corsair. My first TF Corsair was just over 10 pounds and flew beautifully on a Super Tiger .75 two stroke. Put some good aileron servos in it and get that engine dialed in and I think you will be very surprised at how nice the Corsair flies.
Good luck!