The Office of Federal Housing Enterprise Oversight turned up the heat on Fannie Mae with the release of a preliminary report that details evidence of accounting mismanagement at the government-sponsored enterprise that traces back to 1998. The 198-page document was released late Wednesday after OFHEO presented it to Fannie’s board Monday afternoon. The report outlines problems that were uncovered at the GSE during a special forensic accounting probe launched by the regulator in February. Its…