Recently I think my car has developed some slight detonation or possibly my dizzy is going out. After riding around on a normal day when I came to a stop my idle started dropping to zero and back up to 1000 and everywhere in between but the engine seemed to run normal. So ok I get home then it just starts to sound rough, the tach only jumps when I'm at idle and no power loss.
Pull the plugs and noticed the guy at the deaership had given me bcpr5e-11 which is somewhat pretty hot, the base was black but the electrode was fine however the arm was white. I know too hot of a plug can lead to detonation but that doesnt explain the tach.
So anyway, I've since replaced the plugs with 6's so how long must I wait until I can read the plugs again? Couple minutes of idling or do I have to get some load on the engine? Thanks.

 

Dragsters usually install new plugs, make an actual run down the strip, and as soon as they let off the gas they turn the car off. This way you can see what is wrong by looking at the plugs. Hope that made sense.