How much vacuum do you have at idle with that 108CL cam? Does AF change when it gets rougher? And when you say rougher, do you mean it surges a little? Is the Sniper system running on speed density? Can the Sniper control your timing?
One thing I did to smooth out the idle is finite timing control. As you know, changes in timing affect RPM much faster than moving an idle valve. Therefore, when the RPM increased I retarded timing slightly. When RPM dropped, I advanced. This is on a finite scale now. I'm talking tenths of a degree and maybe a hundred RPM.
My engine is slightly more aggressive. 408ci, indybrock heads, solid roller -.594 lift, 278in/286ex, 112 LSA, 9.5:1, Tremec TKO500. I have about 13" of vacuum at idle. I had a much more aggressive cam prior to efi (106LSA) It was way to aggressive for a manual trans as it would make the car "jerky" at cruising speed. I never measured the vacuum with that cam, but I doubt it would have had enough to operate on speed density.
