Just swapped a 98 Ls into my 98 ex, and driving down the road the motor will randomly cut out or "hick up". Sometimes the CEL comes on but it turns off when I restart the car. Any ideas on what might be causing it? ICM or main relay maybe?

 

Identifying the CEL code would (or at least SHOULD) be the obvious first step...

 

I would if the CEL stayed on all the time but it doesn't always come on

 

Read the Codes sticky in the 92-00 Civic forum to learn how to recover the code - see Helpful Tips