Hey everyone! First post and this is my first Jag!

I picked up 76 XJ6 that was a one-owner car until last year when it was sold at an estate sale. It's in pretty decent shape, no rust, clean interior. Unfortunately I'm now the 4th owner, and the last two tried their best to scramble everything under the hood. It's a California car, so it's got Stomberg 175-CD2's with all the new emissions gear for that year. I've got the timing set (10deg according to the manual), and the carbs have been refreshed and have new metering needles (previous owner put the wrong ones in).

Where I'm having trouble is tuning the carbs. I'm new to these Strombergs, and it's my first engine with dual carbs. The only instruction I have is the service manual and Youtube. When adjusting the mixture, if I use the piston lift method I've seen in videos, I can't enrichen it enough to where it won't stumble when I lift the piston. Is there something I'm missing that's specific to the carbureted setup with the emissions gear? I should also note I've gone over every bit of the vacuum lines looking for a leak and haven't found one. It's idling pretty smooth and driving with power, so I know I'm close.