Haven't had anything like this for a long time. Finished reinstalling a new FS9 setup. Used the same cfg file. I have fps locked at 30 and consistently get 29+. But it stutters. It's smooth for maybe 10 seconds and then catches a few times especially when turning. Then smooth for a while. Can't figure it out. Any ideas would be greatly appreciated.

P4 2.8 gig dual duo
4 gig ram
Nvidia 9800GT 1 gig vram