Here are some before (aftermarket performance distributor) and after (New GM stock distributor) waveforms from this erratically behaving Suburban.
Old @ 400 Dist RPM
New @ 400 Dist RPM
Old @ 1000 Dist RPM
New @ 1000 Dist RPM
diag.net/file/f2uon1u8j…
diag.net/file/f5jchyzcc…
diag.net/file/f3ms6nwaq…
diag.net/file/f2zomfxa7…