1405 lean at WOT

Put the A/F meter away.....
Step up rod springs. To select the correct ones for THIS engine:
Start with the strongest set. Loosen the piston cover screw 2 turns, enough so that you can swivel the cover such that you can see the piston but it is still captured. Lock the screws in this position. Warm up the engine, put in gear if auto. If springs are moving AT IDLE, they are too strong. Change to next strongest pair etc, UNTIL pistons do not move at idle. Those are then the correct springs.