G'day Old grumpy
When you say your plugs were only glowing for about 7 seconds is that how long the Glow light stayed on for or was that until you heard the glow relay drop out?

In my MK the light goes out after about 6 seconds but the relay does not drop out until around 11 or 12 seconds. If I need more like on cold mornings I do the old trick with the ignition half on.