older mercedes with the K-jetronic fuel injection need a fuel distributor rebuild along with new injection nozzles at this age and pressure checkup and adjustment of the system. As it is quite expensive business at Shahnawaz motors people look around for cheap mechanics - which never works as they use old junkyard parts which is a very large gamble. Thats why people complain on its high consumption and if equipped as a 230E in a W124 - that car would naturally be lazy as it is quite heavy, If you do wish to buy a W124 - get an early 90s 300E (rare in Pakistan) - the mid 90s W124 (last models) wiring will be degraded and be shorting out by now - its a known fault for mercedes benz of that era - buy only if proper professional repairs have been carried out.
word of advice for the Galant, if the car has a GDI engine - run away from it, it maybe really pretty and have touch screen HVAC controls and nice bells and whistles - that engine will make you cry.
The only real remedy is to replace it with a regular type engine like a mitsubishi 4G63, 6A12, 6A13, 4G93 (regular not GDI). which if you find a competent person who is willing to take apart the dashboard wiring and make it work with the swapped engine wiring.