2001 Nissan Maxima Pulsating brakes when hot

When my Maxima is driven for short distances there is no problems with the brakes. However, if I should drive fon over 50 miles or so, then the front left brake has a pusling when braking.

It seems like a warped rotor, but it does not do it all the time. If I turn the rotors, won't this make the problem worse, since there will be less metal on the rotors?

It does not seem like the front brake is sticking, but how can I tell for sure on a FWD car? Maybe this is causing excessive heat on the rotor.

Thanks,
Tim