Ok now we are getting somewhere. A nice steady 20, in a stock teener say, is very good.
So then pop the pcv out of the cover,leaving it hooked up to the intake. Find a small screwdriver and push the little valve in there all the way in. This is the where that guy should be running at idle;minimum flow. If the idle smooths out and becomes normal than yes I would suspect that valve. But I tell you what; the rattling puzzles me. But for $5 bucks or so,you can try another.
If no change, then I would skip the compression test and go straight to a LeakDown test to prove the valves are closing.See fresh rebuild can mean different things to different people. To me it just introduces all kinds of variables.And valves not closing is one of them.
And we still don't know what engine we are working on.
