I had an issue with my duty cycle running high but it did vary with throttle. It rose as revs increased. I did get cel code 17 o2sensor voltage short to ground or 12v. Look for vacuum leaks I found that the boot between the air plate and the intake manifold had gotten dry and hard and was leaking at the connection to the hoses that go to the cold start valve. Chech those two hoses also they dry out and leak vacuum