I am finding oil to puddle in the bolt valleys of my 350 Chevy manifold. Just in the front two, both sides. Worse on driver's side. It's an aluminum manifold, with a B&M 144 Blower on it.

Also, it has started getting hard to start. I have to crank it over for a bit. Whereas it normally will start right up.

Occasionally when it does start (after having shut it off for just a few minutes, and restart, i.e. fill up with gas) it backfires very loudly...out the exhaust.

Would poor manifold seal do this? I didn't realize it would.

By the way, it seems to run fine once it's started. Doesn't exhibit symptoms of a vacuum leak. But, the backfire, slow starting, and oil puddle symptoms seem to have started pretty much at teh same time. Although, I will say that the oil puddles started first. Then I drove it 1500 miles to Colorado Good Guys and back. Didn't experience the slow start and backfire symptoms during the trip. Just the oil puddling.

Before the trip I had changed the valve cover gaskets to good quality gaskets thinking they were leaking. But the leaking didn't stop, and now the other issues.

I was thinking about pulling the manifold and resealing.

What are your thoughts?