Backing Out Acquisitions

How would you go about assessing the operating cash flow for the core business of a company with a history of making a lot of acquisitions? Mostly bolt-on. It seems to me there is plenty of opportunity for aggressive acquisition accounting that may be giving an incorrect picture of the true earning and cash generating power of the business, and I'd like to try and reconcile it. I've spread the cash flow and balance sheet statements over the past 10+ years and gathered all of the disclosed information about acquisitions over that time as far as purchase price and acquired assets, goodwill, liabilities, etc go, but I'm not too sure what to do from here.

Any advice or guidance?