99 silverado Misfires
 

I have replaced all the plugs with performance plugs and ran fuel injector cleaner through it. Any ideas what could be next? My thoughts are banking on a bad injector, or possibly bad plugwire or coil? I have also heard of a "Knock sensor" which another guy I know of was having problems with, as his plug in one cylinder would be burnt to a crisp within a week of replacement. One thing I did do was run STP Octane through the motor as it said on the label "Reduces engine knock" and it did seem to run alot more smooth.

Is it a knock or a clatter? Need more information...

how about the crank sensor......does it do it when the engine is cold?

It does it when Its cold. Im thinkin knock, it doesnt resemble a clattering noise. Im new. So, well, yeah.

its probably the crank sensor

I would start with the new plug wires and if that doesn't fix it get a compression check on all the cylinders done and a fuel pressure check. Does the miss go away when you give it gas?

Yeah once I give it gas its low range is sluggish, but it kicks in well at mid range.

Then I would definitely do what I suggested above.