My 1997 transport is misfiring.

I did a head gasket job on a 1997 Pontiac transport 3.4L engine and once I put everything back together the car starts but it's misfiring/putting. One thing I notice is that one of the rockers arms is loose and is not making good contact with the top of the valve. My question is can that cause a misfire or any rough idling. I also have the check engine light on and it was blinking probably because of the misfire. Any suggestions on what to look for or what to do. Also does anybody have a picture of all vacuum/ emission hoses and the way they go there is one broken but I have no idea where it goes. Thanks a lot