I changed the plugs and coolant on the wifes 2000 Civic LX, and now there is a bad vibration at idle when in gear. It feels like it may stall, but doesn't. However, it only occurs a max of 2 times on any given trip, no matter the distance. Does anyone have a clue what it may be?

 

what type of plugs? you sure they are plugged in all the way? *shrug* other than that its either in your head/never noticed it before or its not related..

 

Were the plugs pre-gapped?