Just an update on the situation with my car. I had the valve job done a couple weeks ago and so far, no fouling . However, I'm now dealing with the poor fuel economy issue (I get around 10mpg in the city!). As a recap, here is a list of possibly related things that I have changed out so far:

- Cap + Rotor (Bosch)
- Ignition wires (Bremi)
- Spark plugs (H9DC0)
- Ignition coil (Accel 140008, borrowed from friend, didn't help so I removed it)
- Oxygen sensor (Bosch 13953)
- Air filter (Mann)
- All vacuum hoses and rubber fittings, including the two hoses for the ICV
- The two breather hoses (valve cover to air filter housing, valve cover to intake manifold)
- Transmission vacuum modulator

There appears to be no vacuum leaks in the system that I could find with a mityvac and some flammable liquid Lambda has been checked/adjusted and here is what I ended up with:

32-39% at 2500rpm
43-51% at idle

The thing that is confusing me is that searches regarding duty cycle in the forums generally indicate that the duty cycle to be leaner at 2500rpm, whereas my car is actually running richer then. However, according to the landiss page, the main goal is to adjust the idle duty cycle to within 10% of that at 2500rpm so that the system can "self-regulate" or be within its control limits. Am I understanding it correctly, or are my results indicative of something wrong somewhere in the fuel system as I've changed out most of the ignition system? Thanks for your input, and have a Happy New Year