There are several issues here, most desi mechanics would say, change the plugs, throttle body,
I have 2007 AWD, 4G15 lancer, and since I got this car, I took its average from 8 to 11-12 Km/L.
- You might be loosing compression in the engine, get it test for compression. Weak rings are big big issue here.
- Do you have a check engine light? Get it diagnosed.
- Engine Coils, get YEC or genuine coil set from Mansoor Autos
- Use genuine Air filter,
- 10W40 Oil (Aimol powerline) or any Japanese oil blend, along with OEM oil filter.
For AC,
Lancers are notorious for having this issue, they do not have Air cleaning element, especially the ones imported by Dewaan motors. That'd be GL and GLX both 1.3 and 1.6 variants.
Take your car to Mastercool in G-8, they can fix your issue, basically your heater core might be chocked,
Or maybe due to your engine loosing power, the compressor might be tripping.
Lastly your Car Vibration issue in D.
Let me tell you, I have spent thousands in resolving this issue.
Engine and Transmission foundations, throttle cleaning, plugs, coils, tuning.
At the end of the day, it was simple fix, open your Transmission pan, get it properly cleaned (using throttle cleaner) and use OEM grade Transmission fluid, depending upon which transmission it is, you can get it from Mansoor Autos.com as well. Once you do that, the issue gets resolved almost 95%. Basically dirty and low transmission oil can cause the gear to put strain on your engine, ultimately failing all your performance.
I would advice to bring your car to Motorhub in Gulzar - e - Quaid, meet Hadi, the owner of the workshop, he and his team are quite supportive and are not typical desi mechanics.