Need troubleshooting advice; I bought a used vw with Type 1, 2007cc, CB Performance FI system. It ran kinda rough when I got it, I've changed sparkplugs, wires, coil (Bosch), oil and filter. It seems to run better except it stalls and dies at idle after warming up. I believe the vacuum is ok, fuel filter is ok; I'm guessing maybe bad intake gasket (occasional backfire and sputter), or timing, also I don't have sync meter, so throttle bodies may be unevenly set. Any advice? Thanks