Need some information regarding spark plugs.

I just changed my spark plugs from a set of Bosch Platinum’s to a set of NGK Iridium IX spark plugs. Under hard acceleration the car would misfire with the Bosch plugs in. This is why I bought the NGK, I have heard they are the best and last the longest. However; when I pulled the Bosch plugs nothing really looks wrong, I was expecting them to be burnt. Instead there are two with a white corrosion on the tips, I forget what that means. Could someone rectify that for me? Also if the damn thing keeps misfiring what could be the problem? What causes misfires besides burnt plugs? I know that having to large of a gap with too weak of an ignition system can cause this in older cars. Do anybody in here know the answers to my questions?

Thanks in advance ~ Polygon

White spark plugs mean overheating. Here's what I found on a site...

* Incorrect spark plug (too hot heat range).
* Low octane fuel.
* Timing is not set properly.
* Cooling problems, (dirty cylinder fins, no or low water if water cooled, low or no engine oil).
* Carburetor air/fuel mixture is too lean.
* Leaking crankshaft seals, no oil, base or head gasket leaks, or crankcase leaks on two stroke engines.