David Rashid never expected to spend all his free time learning the intricacies of international trade law and tariff regulations.  Yet over the last four years, Rashid, the executive chairman of Plews and Edelmann, a Dixon, Illinois-based auto parts company, has spent hours digging into trade data and combing through Chinese corporate filings, traveled several times to Capitol Hill, and even hired private investigators in Thailand — all in an attempt to prove that Plews’ Chines