I am restoring a 66 coupe, 289 4bbl, c4 tranny. I have an annoying rough idle. I recently replaced the head and intake manifold gaskets, replaced the old autolite carb with a holley 600cfm, replaced all wires, plugs, and distributer. The timing is right on, point and plug gap checks out. Compression is right around 150 all around. I've checked for vacuum leaks everywhere! Even at the modulator. Vacuum reading pulses from about 7" to 25" below 800 rpm, after that it settles out to 25" What do you guys think it is? Can a leaking modulator cause the problem? Any suggestions would be helpful. Also I have the following things left to do: (1) Bodywork/paint, (2)interior, (3)alignment and rear springs. Which order do you think is best?