The idle is good when I started it but after I have drive a bit and the engine has go up in temp, then if I press down the clutch then engine has high idle.

 

So.....it sounds like your Clutch Switch is broken. Here is a thread that explains the Clutch Switch and has some pictures to show you what the problem usually is, with the Clutch Switch.......

https://www.mazdaforum.com/forum/maz...y-53076/page2/

Let us know what you discover with your truck, and it's Clutch Switch!