Oil pressure Failure- questions 1981 scirocco

[scirocco at comcast.net (Scirocco)]

I am experiencing intermittent oil pressure problems since I performed
recent work last week. I can't help to think it may be related. But how?

I replaced my rear crank oil seal along with my clutch.  I also took the oil
pan off and installed a "windage tray". In the process I had to remove the
oil pump. I had no problems with re-assembly, and torqued the pump bolts to
specifications. Additionally, I an NOT experiencing any oil leaks and have
an adequate oil level.

The nature of the problem is bizarre. Some times when I start the engine I
have zero pressure. At other times it is if nothing is wrong and my gauge is
showing normal pressure.

What is the problem?  Just a oil pump going bad?

Anybody else experience this?

David Guido
1981 Scirroco "S"
1980 Scirocco 16v project