First post so I hope this works. Looks like there is a lot of good knowledge tapping into these forums so I'm hoping to find a little. Yesterday i noticed a wierd sound coming from my engine. It starts and runs fine but noise like a loose parts badly vibrating starts at a higher RPM. If I rev the engine a little more the noise goes away, when I drop the RPM to the same range the noise comes back and then quits at the same RPM it started. I didn't check it to many times for fear of causing real damage but it seems to be real consistant at the same RPM. Any ideas?