I have the WCCH 90 mm TB ugrade on my blazer. I'm still working on the conversion but I have been running it in the garage. When I turn the key to the on position the TB has made a very load wining noise . I just figured that this was normal. Well today when I started it the engine it wouldn't idle down. I went to stab the throttle and nothing. First I thought it might be the pedal so I swapped it out and it didn't make any difference.

Then I turned the key to see if the TB was still making the wining noise, no noise. I have been playing with it all morning and I thought I could smell burnt wiring but I'm not sure. Now in the last couple of hours sometimes it works and sometimes it doesn't. All of my connections are tight and none of the wiring going to it has been damaged. Is there a check I can make to try and diagnose the problem or do TB just go bad like this?

 

My LS2 TB has a high pitched whine with key on. Normal.

Yours though sounds like you have some issues