The car runs amazing until 4500-6000rpm what is causing this? At 5000rpm to redline it surges or cuts out?! Please help

 

We'll assume it's the 97 Z28 in your screen name.

Stock of modified?

-ignition breaking down
-running out of fuel
-valve float

 

It's got cold air intake and exhaust. It's 6 speed. And full take of gas

 

If it's the ignition that small plastic rectangle on top of the intake?

 

No, that is your MAF sensor. Ignition module is on the front of the drivers side head.

 

Kevin made a typo....

The small black rectangle on the top of the intake manifold, right behind the throttle body is the MAP (manifold absolute pressure) sensor.

The ICM (ignition control module) is just one component of the ignition system. It also includes the coil, the Optispark distributor, the spark plugs and the spark plug wires and coil wire. Any one of those components could break down and cause misfires.

Here's a site the will show you where the components are on an LT1 engine:

4th Gen LT1 F-Body Tech Aids