I had my engine out a couple months ago and before, I never noticed any blow by or running rough, but now, it's like a can hear a very faint knocking noise. Nobody but me notices it. And when I look at the blowby tube, I can see some blowby coming out. The truck hasn't seemed to lose any of it's original power, just sounds rough to me. All of it goes away after about 2k rpm. Sounds to me like I may have a bad cylinder. But I just don't know and I figured I would ask around before getting a compr. Test.