I have a 02 325xi.. i addition to replacing the coil packs (all 6, spark plugs, Valve Cover Gasket, CCV, pulled the manifold off replaced the intake manifold gasket (hard as a rock), replaced the injector seals upper & lower, CCV system (all the rubber hoses) Secondary air hose from the pump to the manifold, the brake booster hose upper & lower intake boot and cleaned the ICV & Fuel pump & fuel filter. Also replaced the entire cooling system and Precat 02 sensors & DISA. It has been flawless for 15k miles after the above. I ran the gas down to a gallon yesterday and the check engine light came of for misfire.. After 200 miles of highway driving after filling up with a full tank the light went away. Everything was original on this car when I first got it.. With each refresh of systems it runs better & better. Sounds like you may have one or several vacuum leaks.. Is the valve cover have a hair line crack in it?. Is the entire CCV in excellent shape? How are the parts above that were changed? Have you checked compression? Checked fuel injectors? Fuel Pump, Fuel Filter?.. Hope this helps.. P.S. post the exact codes it's throwing