1996 Gtx won't go past 4k rpm

[JasonKozofsky]

My gtx was running good but recently it hasn't been going past 4k RPM. I also notice a whistle noise when I give it full throttle. I cleaned the RAVE valves and it didn't seem to help. I also noticed there is now a big buildup of black where the exhaust manifold connects. I attached a video and picture https://youtu.be/vdrZiueNoek

 

[mikidymac]

You have some kind of bad exhaust leak. You need to find where it’s coming from as it will starve the engine of oxygen and will choke itself out.