I converted a McDonnell XP-67 model from fs2002 to work in cfs2, i replaced the airfile with a modified p-38 version and its engines ran, i then proceeded to taxiing and when i got up to about 20kts a small swing started, i was able to correct this with rudder. as i passed about 40kts however this swin became unbearable, the craft swung from one side of the runway to the other with no vestige of control.

can anyone give me any ideas to fix this, should i, for example replace the .cfg as i did the .air file?

the model is off www.fsimcafe.com and i will provide any extra details i can.

can you help?