I have been trying to trace down a low power problem with the car. After about 20% throttle you can push the pedal down further but the car never accelerates any faster. Being pre-Lambda I put a O2 sensor into the exhaust and wired up a cheap A/F meter. What I found was that at idle the motor runs very rich, and as RPMs go up the engine runs lean. It's as if the fuel isn't increasing as more air goes into the motor. So off idle the car drives fine but the further you push the gas pedal down the more lean the motor runs. I pulled the intake boot and checked, the air flow plate moves freely. What's the next thing I should check or do to get my fuel back? Thanks for any advice.

~Mike