Hello!
I'm sorry if my english isn't good..

Today I changed my VICS intake manifold on my NA8 miata in order to put a Squaretop mani.

Previously, I've cleaned the interior of the intake mani with brake cleaner and I dunno if the gasket was in good shape but I think it was.

Before I put the squaretop manifold on the car, I disconnected the battery in order to avoid an electrical problem.

After the manifold assembly, I started the engine and I heard a air leak who seems to come from the middle to back of the IM. I sprayed brake cleaner in order to search where is the leak but me and my friend doesn't found the air leak.

When the engine started, the RPM goes to 1500rpm during 20-30 sec and after that drop to 850rpm (which is good).
When I drove my miata, during 5 minutes after the start, for example when I stop to a tricolors light and do the neutral gear, the rpm at idle stay during 5-10sec at 1500rpm and just after fall to 850rpm.
When the engine is warm, no problem, the rpm is always good (850rpm) at idle. No problem when WOT, the car is ok without hesitation at the acceleration or problem like this.

Am I mad for the air leak or is this the result of the squaretop manifold noise who breathe more?

I dunno...