Fuel System
WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
Test for leaking fuel injectors. See FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL or FUEL INJECTOR BALANCE TEST WITH TECH 2 under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4.6L DEVILLE & SEVILLE article.