i'm hearing this like knocking sound from my motor every now and then... but, the thing is... it's only under a high load and full throttle... i pulled the plugs and turned the motor over and it all sounds normal the pssh pssh pssh sounds constant on every plug hole with only that plug out ex: trailing front rotor spark plug out and the rest of the 3 in and not hoooked up to the coils... just to test the compression WITHOUT a compression tester... i know i need to get them tested but, i mean i keep my car good and tighty... i change the oil every 2,500 or so and new fuel filter and new plugs, new wires, clean motor, i ran motor clean a while ago and did it again recently... i'm sure that's NOT what made the motor do that knocking sound but, it's sounds kind of like a metalic knocking sound from the engine bay somewhere and it's not the alternator or any of the belts.... the alt. is new and all the belts are new... and i just swithed to synthetic blend... but, it was doing that BEFORE i switched the oil types... it doesnt do it all the time sometimes i can go a day or two without it doing it but, it only happens when i'm under a load and pushing the motor above 4,500 and it doesnt lag at the hesitation point.. it pulls hard even when the motor makes that clicking/knocking sound.. I dont get it oh, yeah i just broke a 105,000 miles on a 1990 vert... if someone could help me out on this it would be greatly appreciated... I hope to god it's not my apex seals.... ahhhhhhhh.... Expert help please....