My SC1 occasionally shakes when idling after initial warm up. It sounds like the engine is going to stall sometimes. It is happening more frequently. Plugs were replaced about a month ago. The car generally runs fine, but when you come up to a stop at a red light, once in a while the RPMs drop suddenly and like I said it sounds like it could die. Car is a 5 speed manual with only 34K miles if it helps to know. Any ideas? Thanks in advance.