Hi guys,
I know that some of you guys may have a good idea on what my problem may or may not be. My lt 4 has a slight miss starting around 3000 rpm. The engine also seems to change the pitch in noise at that rpm. I use 93 octane fuel, no ethanol. 35000 miles on the car. All original except new air filter. The intake manifold gasket was changed about 5000 miles ago. The miss is detected only if I maintain speed in lower gears around 3k and higher. It doesn't seem to miss if accelerated. Hate to change plugs and wires and find out it was something simple. No idiot lights come on. Could the noise in the engine be just the resonance in the mufflers at that rpm? It's not a nocking noise.

 

Better get a scan for measurements... Most tune problems are noticeable at idle, and less noticeable at higher rev's...

 

Got a scan today. No missfires recorded. No problems showed up. We are getting a injector cleaning kit from a chevy dealer and run that thru it. Hope that does the trick. Anybody have any luck with this proceedure?