Recent swap/ new headers/ check engine light
 

So I have a 98 civic ex and I recently swapped from a y8 to a y5. The swap went fine. No check engine light and motor ran fine. I took off the intake for a day and it drove fine, however with a check engine light. Is that because of the intake? / And I just put new headers on it today. And I noticed when I go to turn it on it has a hard time starting and then on top of that the idle fluctuates. The car will drive, but it will fluctuate when I attempt to ay the radio or turn on headlights. Someone help.