I think I have finally got it. Turned out to be a couple of things. First, the PCV valve was indeed the wrong one (thanks "just a six"), even though the auto parts store assured me it was correct. Secondly, the throttle shaft of the "reman
" carb was leaking baddly on the thottle linkage end. I had my original carb's throttle shaft rebushed and rebuild by a quality local shop and Bingo! Now the 250 idles so smoothly I can't even hear the darn thing running.
Thanks for all the suggestions guys!
