I downloaded the external FPS Limiter and unzipped it, double clicked on the FPS Limiter.exe file and saw a flash of what looked like a command prompt screen. It does not stay on. My file manager says it is running but I don't know for sure and I am not able to set any settings. Anyone got any ideas about what is going on? While running FSX with internal FPS set to unlimited and flying the FPS are running in the 50s to 60s and are not steady.

Do you have an Nvidia card?If so just use the new built-in frame limiter in Nvidia Inspector. :)

I do have an Nvidia card. It's a GTX 285. I'll take a look at the inspector. Thanks for your reply.