99 Taurus won't start... Sometimes

My 99 Taurus won't start sometimes after a 20 minute or longer drive, basically when it gets hot. No noise or anything comes from the starter. Ussually when I let it cool down it will start again. I get power to everything else radio, lights, etc. I took the battery and starter starter out and had them tested and they tested fine. What else could it be? Ignition switch?

check the starter solenoid and the starter relay.

I had the same problem on my 99 Taurus last year. When it had run 20 minutes or so, it wouldn't start. If I let it cool, I could start it (barely). If this is your original battery - replace it. That's what was my problem.

Thanks for the info... The starter solenoid is on the starter right? Where is the starter relay? I didn't know there was one?
Thanks

check the starter solenoid and the starter relay.
Found the starter relay and I think that is the problem...
Thanks for the help! I will let you know if that it the problem.