Kary,<P>Thanks for the input.<P>The problem came on fairly quickly, about 2-3 weeks ago. I noticed a valve chatter for a few days, then the oil pressure dropped. Since the rebuild, the truck just doesn't burn any oil, so I hadn't checked it for the past 6 weeks. I added the oil back, and shortly after that the "sticking valve" behavior began. Prior to that it was just a slightly rough idle, since the Rubicon. The idle's smooth now. The "sticking valve" behavior can be intermittant, and avoided by using 2nd gear in the city. <BR>I'm wondering if I've got some floating crap in the carb inards, or even a blocked venturi port which is interfering with the secondary.<BR>I'll change the oil and filter, and the dist cap and rotor, and then try another hiway run to see if that helps...<P>Thanks...<P>Don