When I drive my mazda on longer stretches of highways of speeds excessing 50-60 mph I sometimes lose power. I can feel car slows down all of a sudden. I can mitigate by letting go of the gas pedal and then pressing it down again and also by flooring it. It doesn't respond for a couple of seconds and then jolts back to life.

It never happens on shorter drives. Only on longer drives (> ˝ hour) and at high speeds.

I've tried speaking to a couple of mechanics about and they haven't had a clue on what the problem was - except perhaps that it my be the spark plugs that need changing.

Any suggestions would be greatly appeciated.

Kind Regards.