First Let us know why would you change your FPS and make it lower?
Well you need to match your Shader Graphics to your maximum FPS. As you have set your maximum fps to 70 you need to set your Shader Graphics to 71. (Good Textures, Car Reflection Shader, and Detail Shader)My maximum FPS is set to 77 and I have set my Good Textures, Car Reflection Shader, and Detail Shader to 78 which is under the Shader Graphics.Here is an screenshot for better point of view and understanding: https://imgur.com/Bim8oFT
also a notice [ I did what u said but there is once thing I have to make the detail shader lower than 70 so it makes details better thats bring back the problem