If you upload a replay of you doing some laps we will be able to help you much easier. You can do this by:
1. Drive some laps in single player mode.
2. Press "2" and save the replay with a name you can easily notice and remember.
3. Exit LFS and post a reply here, and upload your replay which will be saved in your LFS/Data/spr folder.
I have attached a good setup for this track which I used to run my PB of 1.13.09.
Good luck,