MOR404, sorry to read that your Mog is not running as you might wish despite resolving your carb issue..I guess an other question is did it ever run to match your expectations of it..?
Modern cars have so much complexity built in to ensure smooth running in all sorts of situations that are far outside the capabilities of any elderly carb fed engine which may be less than comfortable while running on the choke, which it`s self may not be operating perfectly if automatically controlled..?
Your car is nearly 40 years old, it has spent a lot of time with it`s engine and much else not in use and depending on climate, corrosion can play a part, which can cause it`s own wear and tear issues thus mileage as recorded in the speedo may not be taken as a true assessment of condition. Also that you have only owned it for 2 of it`s years (?) you may have no idea as to how it has been cared for over the previous 30 or so years..and as I hinted before it is also possible the engine has been subject to some modifications..? Fuel quality and dependant on whether the engine has been modified to run on whatever fuel you use can play a part.
Perhaps a compression test may be worthwhile to help you partly assess the engine`s condition..?