Help... Please. 2011 Subaru Impreza 1.5

Hi everyone. Need help.. Please.

Recently bought a 2011 impreza with a 1.5 litre engine and with 78000 kilometres on it.

Car runs great, except for LTFT around 9 to 10, 15 ignition timing and worst part is I get around 10mpg / 5.5 kmpl. A full tank of fuel only gets around 300 kilometres. LTFT at idle is close to 10 and goes down to about 7 when AC is turned on. When driving, LTFT is around 2 to 4.

Checked for vacuum leaks, (found none) smoke tested it too. checked and clean EGR valve, cleaned MAF Sensor, (which reads around 2.2 to 2.5 at idle with ac off, around 3 with ac on. Rpm at idle is smooth and around 650 with ac off and around 850 with ac turned on. Fuel flow shows around 0.8 liters per hour with ac off at idle and around 1.7 liters per hour with ac on. Reset ecu (removed negative terminal and left off for about an hour, 10 mins run, switch off, run 5 mins, switch off, etc) lambda sensor shows value of 1.0 at idle and voltage of around 2.2

Please help guys.. At wits end and have no clue what's going on.

There is a slight hesitation off the line when accelerating but starts pulling hard around 2000 to 3000 Rpm. Strong exhaust smell, not necessarily a fuel smell but a stinging kind of smell.

Any ideas anyone?

Any advice would be very helpful and very highly appreciated.

Thanks in advance.