[NYSCAR]

Hmm the same two cylinders every time? Are they not firing at all? (i.e. if they never fire, the plugs will be wet and sort of clean from all the gas washing them off). If so, work your way backwards, swap the non firing plugs with ones from the firing cylinders, check your leads to make sure they're seated well, replace the distributor cap if it is old, check for play in your distributor shaft. Other sources of failure can be ground strap, CDI box, coil, etc but usually these are random misfires (not the same two).

Brad