Ok here goes.
My air filter and plugs were just as bad as yours so I changed them and put new ones. I changed the air filter from a Shell Pump and paid about 300 rs. Also changed the oil filter and put a toyota one when changing the oil, this too from shell pump at clifton. The plugs (Rs.150 each), atf (rs. 378 per can used 2.75 cans but had to remove some as they filled in extra) and labour was about 1,200 with car wash service. This was done at Toyota Society at Khalid Bin Waleed road.
The guy at Prime Defence I spoke to Mr. Farid said he would charge me Rs.300/- for the onboard diagnostics checkup and if anyting needed replacement cleaning etc then separate charges. He said he would clean the throttle body and the pick would improve considerably. You can speak to him and give my reference if he still remembers me
About your mileage, its definitely rolled back but as long as the engine is in good condition then its perfect. Avg. mileage per year should be about 9-11k kms.