One more comment. I was reading on the web about the stepper motor / metering pin function. I did a test as stated on the web. Anyway...while the engine is running the metering pins do not move. The article says that they should move back and forth. My metering pins are fully forward and not moving (rich position) while idling. The next test I did was to rev up the engine and close the choke plate until the engine gagged. This forced a rich condition and sure enough the metering pins moved backward. The article states that I should be looking at 1) non functioing O2 sensor, or an air leak or vacuum leak.