2002 Audi A6 Bent Valves replaced still misfiring

Hi,
My car stopped after a few weeks of running idle, and cutting off randomly. CEL was blinking when also. Took it to a shop where my timing belt was horrible ( I think it jumped a few teeth) so I recently had my timing belt replaced ( full timing kit to be specific), spark plugs, and coil packs replaced, still random misfiring though on cylinders 2, 4, 6, and 7. So I had bent valves replaces and head gasket replaced and still random misfiring. Any ideas what it could be? I have put almost $2000 into this car and it is still not running smooth. Car cranks up and mechanic says motor sounds good.