I have an 89 LX with a 306, TFS Track Heat heads, Track Heat intake, and TFS Stage 1 cam. The engine runs great, and makes good power, but when it reaches 5800-5900 RPM, it makes a funny noise back into the intake, almost like the intake valves are open too long, and instantly falls flat on power. It actually could rev higher than this with the stock cam, and this doesn't seem right. I installed the cam "dot to dot", and was wondering if it would help to change it to 4* advance or 4* retard on the crank timing sprocket, but I don't want to go through all that trouble to move it the wrong way, or to have it not make any difference. I have also tried moving the timing, changing the distributor, and my plugs/wires/cap/rotor are all new. I also run a MSD digital 6 ignition, and HVC coil, but I have tried switching to the stock coil/ignition with no improvement. I have a 150hp NOS system on the vehicle also, but I am afraid to use it with the engine acting like this at high RPM. I have also tried a different computer. Any help would be greatly appreciated! Thanks!