Posting here for a friend because he's not able to find much of any other support online for his car and the majority of surviving 400Ms are in trucks, so people here would know about them.

The car in question is a 400M powered 1972 Ford Country Sedan station wagon (think stripped Country Squire and you have the idea). It has just 46,000 miles or so on it. The stock 2 barrel and intake were immediately removed when he purchased it ~6000 miles ago and replaced with an Edelbrock Performer 400 intake manifold and a locally rebuilt Carter AFB 625 4bbl carb. The points were replaced with a Mallory 61002M points replacement system. Otherwise the car is mechanically stock; it was filled with Shell Rotella T 15W40 oil before it left.

The carb was overhauled, installed and tuned by a competent mechanic in Joplin, MO. It was then taken on a multi-thousand mile US road trip during the month of October before being shipped to my friend's home country of Germany where during the process of adapting it to local regulations, the carb was adjusted by a local Berlin mechanic using an exhaust gas analyzer as it was thought to be running a touch rich (and European fuel prices being what they are, that's not a small concern.)

His problem is that after this adjustment, the car seems to be lacking power and consuming more fuel in certain regimes than it was in the US.

While he was driving it here:
Ambient temps between 50 and 75F
Interstate driving, average 75mph indicated, '13-ish' MPG
Highway driving, average '50ish' mph indicated, '14-14.5' MPG
City driving, average '30ish' mph indicated with stop and go, '10-11' MPG
Car had torque everywhere and didn't seem to struggle.

Over in Berlin, post 'adjustment':
Ambient temps between 23F and 50F
Interstate driving, average 75mph indicated, 11.5 MPG
Highway driving, average '50ish' mph indicated, 9.5 MPG
City driving, average '30ish' mph indicated, 8 MPG at best, often 7MPG or worse. (His Berlin 'city driving' has been just four to six mile hops so it's likely that the choke's still on and affecting the fuel economy that way.)

Some of his comments on how the car is behaving:
Sooo... anyone have any idea what this setup *should* look like on an exhaust gas analyzer in terms of air fuel ratio? Should he just start over with default settings and work on settings from there? While we know his settings are now messed up, should there be this big a drop in fuel economy with a drop in temperatures like this? Any help would be appreciated.

 

Ok, this is what typically happens.....

in a perfect world, with the air/fuel mixture set according to the "meter", on flat ground, typical ordinary driving, yes, it will run fine & get better mileage. Now for the real world, with carbs, they really need to be set (in most cases) slightly rich....this provides better accel which means less throttle typically used and ie better mileage, etc.