i have a 1996 chevrolet silverado 1500 pickup do this truck have fuel injector?

What is your question?

number 5 cylinder have a misfire and sometime the engine service like blink the misfire is mostly at idle speed i change number 5 spark plug i put it in number 1 cylinder and i put number 1 spark plug in number 5 cylinder and the misfire is still in number 5 cylinder that didn't stop the miss when i take number 5 spark plug out it is real white on the electrode is that a sign the plug is to hot what cause the plug to look like that? this engine dose have a throttle body.

How long has your 1999 Chevrolet Silverado 1500 had this problem?

a few years