My car runs perfectly when driven normally, however whenever I get up to 90 in 3rd gear (around 6500rpm), my check engine light starts blinking. This means that my car is misfiring, correct? Is this only happening because at that rpm I am really straining the engine? Do I need to have anything checked, or just not rev her that high?

Thank you!

 

Check your plugs and wires. And yes it seems that you have a misfire.