Leaky Valve Cover Gasket

[Ang]

I posted the following elsewhere, but thought I'd re-post here to avoid hijacking someone else's thread:

My '91 350sd has an oil leak, which looks to be coming from the valve cover gasket. Looks and sounds like an easy enough job (did the same for a Mazda 929 once), but I want to make sure I'm solving the problem.

Some mornings the engine runs very rough and whitish smoke comes from the tailpipe. Can a bad valve cover gasket cause such a problem? Makes me wonder about the head gasket (please, no!).

TIA.

Ang