Help, No Start

I replaced my exhaust manifold this morning and after I hooked everything back up the engine won't start. All the vacuum lines are in place, all sensors reconnected. The fuel rail does have fuel in it, and it has air. What else could be causing this. The starter will turn but the motor won't catch. I'm stumped, everything is just like it was yesterday when I pulled it into the garage. :dunno:

have you checked spark? Always check for fuel, spark and air first.

It definitely has a spark. The rail has fuel and the throttle body is working.

did you pull the battery cable to clear the computer out? wierd

Ok, I got it working. When I checked the spark I had spark, but I never thought that when I cleaned the head ports that some of the crud might have fallen into the valve. I pulled the spark plugs out and they were covered in build-up and gas. Sprayed them off with some compressed air and it fired right up.