Accrual for under billed projects

All:

I would appreciate some guidance to anyone who has design/build going on in their firm...  We are a medium sized firm with two departments, one for design, one for construction (primarily CM).  Each month we analyze our billing and determine which bills can be sent and which cannot (for various reasons, usually due to us having done the work but not yet having received a PO from the client).  We do some lump sum billing but a lot of our work is a guaranteed maximum price and billed T&M. 

The owner of the company would like to find a way to minimize the fluctuation each month of adjusted income so that it is more level month-to-month.  We conduct an accrual process at the end of each month and adjust our income, but this seems to compound the problem rather than make it more streamlined.

I'm looking for any resources you might know of (book, website, consultant, etc.) who might be able to assist us in trying to get our monthly numbers to be more in line with each other.

Any assistance is greatly appreciated!  Thank you!

-Siri Heinrichs, Berkowsky & Associates, Cranbury, NJ