Rough Idle/P2610

[Mythic Top Hat]

Hello, I'm a new user because I need help, I have a 2004 Aveo with a 1.6L. Recently the head gasket started to leak so me(thinking I'm a better mechanic then I am) decided to replace this myself. Long story short, got the new gasket in place and everything back together including a new timing belt. Started her up and she has very rough idle , it stays running but barely when rev'd past 1500 rpm or driving it runs fine, the check engine light didn't come on but it pulled a code of P2610(ECM/PCM Internal Engine Off Timer Performance). From what I've read this doesn't really cause rough Idle? Is this true? Or am I going to have to computer tuned, or did I just mess up the timing(all the marks seemed lined up good)? I know it could be a number of things as simple as a vacuum leak(sprayed starting fluid and it didn't rev up). Just thought I would throw it out there and see what others thought. Thank you for you time! Should also mention it need about 1/4 throttle to start.