Uneven exhaust question

[jnikolas]

I have a 400 sbc motor that I just replaced the mufflers on. The old mufflers were completely rusted out so I installed 2 new Flowmaster super 44s. I checked carefully for any leaks and sealed the one I found on the driver side. I found none on the passenger side. The driver side exhaust is very even now. The passenger side exhaust is choppy. When I put my hand to the tailpipe I get two to three strong blasts then one beat of no exhaust coming out at all, maybe even sucking. This is at idle, I have not tested at higher RPMs. The engine runs well except I do notice a tiny loss in power at one point in rotation. I am guessing one of my cylinders is having a problem on the exhaust stroke, but I have no idea. What can I do to test this and to repair. I appreciate any help.