I am having a problem with the Holley 4160 on my C2 Corvette (year withheld because some may consider it O/T). I'm asking here because there is more knowledge here than anyplace else I know of. Anyway, the car had been sitting for about two years waiting to get a set of heads with a new set of valve guide seals installed on the "freshly rebuilt" engine (life had taken a major downturn in the interim, causing the delay). I finally got it back together this spring and it ran terrible (it had been running perfectly before, but was burning a quart of oil every two fill-ups). I took the carburetor apart, replaced the accelerator pump diaphragm, checked the power valve, and cleaned everything up. I put it back together, and it ran much better but would have an occasional stumble when accelerating, and even once in a while just cruising at a steady speed. In an attempt to figure out what was happening, I removed the air cleaner assembly, and the engine ran perfectly with no stumble. I had an almost new K&N air filter on it, so I put it back together with a new conventional filter. I took the car out, and it was considerably better; for the first 10 miles it ran great; then, after a hot start at the post office in town, it stumbled a couple of times more. I can live with it the way it is now, but I know it ain't right. Previously, I had spent considerable time on this carburetor ( used my surface plate to ensure the surfaces were flat, set the float levels; everything I could think of and it ran great before this hiatus. The carburetor has #61 jets (new, as the previous ones had been drilled out), a 6.5 power valve, and I am at about 950 ft elevation. I am thinking maybe I should lower the primary float, or maybe replace the power valve with a 7.5, or even jet it down. Before I start down one of these roads, does anyone out there have any insight as to what may be going wrong and where I should start?