Toyota Repair: rough idle, wet weather, wire connectors

Question
Hi Ted. I just wanted to double check your previous recommendation b4 I bought the new ignition coils. My 1998 corolla engine light hasnt come on since I replaced O2 sensor back in March,no pending codes either when I checked a few times. Car vibrates/shakes when I come to a stop, if I shift into neutral the rpms go up slightly for a moment then it settles back vibrating. In neutral it shudders for a moment, stops for a moment then shudders again. There seems to be no difference in very wet weather which is why I wanted to double check with you, that and the fact that the engine light hasnt come on to indicate misfiring. The only other strange thing going on is when I am maintaining a steady 40-50 mph speed occasionally it cuts in and out, feels like the car is surging. If you still feel the ignition coils are the likely culprit I will replace them this week. Thank you for your time and expertise sir. :)

Answer
I don't think the coils are the problem with no check engine light on. First check the distributor cap and the rotor for cracks, remove the plug wire connectors and check them for cracks or signs of arcing, I would replace these items and the spark plugs first if they haven't been replaced in a long time.