Hi
Was the vac reading off live or actual ? have you cross checked the two.

You checked the cam timing, but did you look to see if crank pulley had moved on crank ? I agree compression test it vital next step

A pre sensor leak could cause the emission fault, but not sure would have such dramatic effect on vacuum.

Interesting that the Lambda reading was OK, surprising with such high CO. Can you post the oxygen reading and lambda sensor voltage reading

Cheers Aidan