Car is a '97 960. For a while I've been experiencing a low rpm miss under load. It only is apparent under 2k rpms, so the only times I feel it are when taking off and if I open the throttle a decent amount at about 40mph with the torque converter locked up. It definitely seems like a spark miss as it's quite erratic and harsh. It also comes and goes (seems to be correlated with humidity, which again, seems ignition related). I've been hoping i could get it to miss bad enough to set a P030X code so I'll know what cyl to look for but it's not constant enough for that to happen. So i guess the next step is pulling all the coils out and visually inspecting them. Some background info. The plugs and the intake manifold gasket have about 15k miles on them.

Are there any common tell-tale visual cues to a bad coil on these cars?