So I stumbled upon this by accident yesterday and am not really sure how to proceed... When idling the car or coasting in neutral, if I repeatedly press the brake pedal I can literally watch the AFR's on my gauge go to full lean. It doesn't need to be pressed in hard either. Doing the same w/ the clutch pedal does not cause any issue. I'm thinking it would have to be a vacuum leak with the brake booster or something? Brake fluid level is still at the full line so that's not leaking. Any ideas?