vaccuum in valve cover

[budscuz]

Just got my '96 Bonnie 3800, naturally aspirated back together. It had gotten too hot and blew out head gaskets on both banks. Started right up and run sweet. I popped the oil fill cap to set the cowl over the engine and it got rough, almost stalled. It's sucking air...big time ! I don't even know where to start with that. Put the cap back on...runs sweet. You guys have any ideas? Thanks

[Jrs3800]

Look for the PCV and or O-ring... If one or both are missing that could cause your vac leak when the oil cap is removed...