2001 Kia Sportage Car doesn't start sometimes.

Sometimes when I try and start my car it won't start or even turn over. It's like the batteries dead but I checked the battery and its fine. The lights won't come on or anything. I sometimes have to sit and wait 20-30minutes before the car will finally start. I took it to a repair shop 2 mths. Ago and they said it was two sensors that needed replaced. A week later my car started doing the same thing until eventually it didn't start at all. I had it towed to the same repair shop and they said one of the sensors was bad & they replaced it free of charge. A week later my car returned to not wanting to start. No car place seems to know whats wrong with it. Some have suggested it's an electrical problem & that the sensors should have corrected it. Could it be the battery even though the battery is showing that it's good? Whenever I get into my car I always have to reset my clock and radio(this is after my car finally starts). This is another reason I think its the battery. Could it be a fuse?