intake manifold air leak after pcv

[855 tdi]

I did my pcv months ago but the car had problems which sounded like a small explosion, it would rev as and when it liked sometimes instantly upon start up up to about 5k and other times it would have the rpms get lower and lower until it stalled. My suspicion was an air leak as the throttle made it rev wildy with even a small input. It's been sat on my drive since then looking sorry for itself.

Finally got around to removing the intake and I believe you can see proof of the scorch marks, the problem is why did it have a gap in the first place, is there a certain order to do up the bolts? Should I use some sealant for added precaution? The only reason I can see it to have a gap that end is the bit of metal holding a pcv pipe out of the way. I need it back on the road asap as my 940 needs work doing that will take it off the road.