I was wondering if it was a twin. I have a bad habit of trying to take off with one engine and end up spinning around lol.

Hmm... the WW2 Corsair from Blue Ciel that I had for FS9 was a beautiful, wonderful beast...lovingly recreated...including the insane torque it produced on takeoff! I literally could not take off at more than half throttle, or I'd crash! I think the WW2 Mustang was similar too, beastly power at takeoff.

Another thought: go to the keyboard settings inside FlightSim, and reset the values to "Default"...maybe one of the keyboard settings was constantly set to 'turn' the plane?

I'd try and trim it out, I dont know how experienced the OP is at all things aviation but single engine propellor aircraft have a tendency to want to turn due to the effects of the propwash on the tail of the aircraft. IRL you need to stand on the rudder to keep it heading straight down the runway and after take off other wise you get a real sloppy departure. Once you put more speed on the plane and leave maximum power settings the tendence to want to roll / yaw lessens but you will still need to use a bit of rudder. Try looking at the slipball and see what that is doing, if it is off to one side try and center it with the rudder.