Ok here's what I got so far...
The first thing I checked was the hot idle compensator. As I said in a previous post, the cover has a rod coming out of it with a little spring attached. This was specific on Oldsmobiles but I forget why. I soldered the end of the rod so it wouldn't move in and out with the vacuum but it broke loose. So that caused a vacuum leak. I cut the rod, soldered the hole closed, put the compensator back in and put the cover back on.
Next I checked the idle adjust screw without the spring so it would close off a little more and that worked. I didn't want to leave it without the spring so I put it back on and tried the next test.
I lowered the idle really low, about 1/4 turn above sputtering and closed the fuel idle screw and the RPMs went down.
I brought the idle back up and tried the adjusting screws again with a vacuum gauge. The pressure changed as I adjusted the screws. It's sitting steady at 15 and seems to be idling nice and steady. The hole in the back of the hot idle cover may have been the issue.
I haven't pulled the carb to adjust the float yet. Cliff's book says it should be set at 1/4" so I'm going to have make that adjustment. The book also says to toss the little clip on the needle because it's not necessary so I'm going to remove that too.
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