Originally Posted by KarTek

You can tell if a plug is dead when starting on a colder morning (<50) because the engine shakes and runs like crap for about 2 minutes and then the offending cylinder will come to life with a series of "tack...tack tack...tack tack tack" sounds.

The GP relay is on the top of the left front fender - a black box about 4x2x2. You can pull the 6 wire plug and test between the pins and ground to locate the one with the odd resistance. They will all be within a couple 1/10th ohm of one another.