Coolant leak- Intake manifold or head gasket?

When beginning to adjust the valves and replacing the valve cover gaskets, I retired for the night and came back the next morning to having the number 6 cylinder full of coolant all the way up through the spark plug tube. It puked it up when turning the crankshaft manually. It's doubtful I had any of these hoses leaking through the top of the air intake, but as you can see that towel is the only one showing coolant absorption. When I was removing the bottom half of the plenum, I did josel it somewhat because I forgot to take out that longest bolt that was the one remaining before I found it and removed it quite easily. I didn't move it too hard or anything. I can't tell you if my tailpipe was spewing white smoke when running the engine before this. The Tacoma has been having hard starts the past half a year, and finally got around to doing some valve work. I'll be cleaning the garage and preparing to lift up the intake manifold here soon.

I'm just wondering at this point if it's the head gasket or the intake manifold leaking this coolant. Any ideas?

 

If I had to guess I'm pretty sure the intake manifold leaked into cylinder 6. Still don't know exactly what I'm doing as this is the first time but if I deduce this correctly it looks like that coolant channel leaked into the number 6 cylinder from the intake manifold when it was slightly loose. This would be great news. I'm assuming that coolant in that pool in the center isn't supposed to typically be there either and it leaked in.

 

Did you drain the coolant before removing the Intake?

 

I did not apparently nor did I intend to but I did take the radiator hose off