I've changed my ignotion coils before but I always wait until one completely goes, I feel one starting to go now because the car is stuttering a little, is there any way to figure out which one it is since when one usually goes, you will not get a spark when you do the test, in this case I assume I would still get some spark

 

anybody

 

unplug coils 1 at a time cking for rpm drop, no drop = bad coil
have parts store ck codes for coils-misfire codes
ck spark plugs,,one not firing right will look different

have you cleaned the egr system,,99s really bad about early clogging,
and it makes car idle rough