It`ll show if its bad or not, by the resistance value...
I have yet to run across a coil, that had correct resistance values, and not work fine (primarily motorcycle coils, same thing pretty much, a coil is a coil..EI coils usually average around 3ohms or less...points coils, are in the 5ohm range)..I think the vmax coil, is around 2ohm? would have to look in the book..
typically, a plug reading rich...when its caused by a weak coil..will show on a ohms test..
I just have a feeling, the problem you guys are having, is not gonna be coil related...from what I`ve gathered on here over the last few years, i can`t recall off hand, anyone having a stock coil go bad?
but as i mentioned above, them caps to wire connections, can get cororaded, and cause weak fire...
AL P