1998 Silverado 1500 5.7L wont turn over checked starter and power to the starter all good Pulled plugs and turned crank manually and still no turn over any ideas?

I have jumped the power to the solenoid before with a screw driver or something to test them out (beware this will cause some sparks where safety glasses). Also if you can remove the starter some parts houses will test the starter for you. If it works you can rule out the starter as your problem.

Also, remove and clean both battery connections. I had the same problem and I found the positive connection had some corrosion in the threads of the side post battery. I was unable to see it until I removed the post. It was just enough to where the truck wouldn't start.