Let me give you guys the specs. I just got working on a friends 98 coupe with a Y8 in it. After changing the head gasket and starting it and what not I hear this wierd noise coming from the valve cover. I immediatle ask him to shut it off and then I took off the valve cover to inspect. One thing that I noticed was that one of valves was stuck down. i played with the valve and then I was able to make it pop back up. After that I notice the rocker arm for that valve was not sitting flush on top of that valve. On all the other valves the rocker arm was sitting flush exept for that one stuck valve. Do you guys think its a bent valve

 

most likely its bent

 

was it backfiring like crazy?

 

I'd say it's a bent valve if you rotated the engine at all with the belt off. These are interference engines so turning the crank and not turning the cam makes the pistons "interfere" with the valves....

 

Maybe you didn't get the belt back in the correct position, if one of the pistons hit the valve, it's bent. check your timing before you take it apart again.

 

The timing is dead on. And the engine runs smooth, until that one valve gets stuck then it will misfire. after a wile the valve will unstick itself and start to run smoothe. It seems to me that the vavle bent just a bit and causing it to get stuck in the guide.