Engine Performance problem
Mazda 323 4 cyl Front Wheel Drive Manual 99000 miles
So I have this 2nd hand Mazda which was in a very poor condition(loose compression), unstable rev, burning oil, too much smoke coming out the exhaust, dies in the middle of traffic etc etc. It undergone general-overhaul, they say it has new sleeves now, piston rings, sparkplugs, oil and so on.
But to my disappointment, after paying a load of money for the new parts and machining works, the car is still performing below average. I can hear from inside the car the ticking of the valves but they say that's just okay. What's bothering me is the acceleration is weak, (definitely not like before) when I hit the gas, it accelerates slowly but can reach fair amounts of speed but longer period of time than it should. Another thing is when it's idle, neutral or clutch down, the rev is unstable from 750 - 1000, the annoying thing is the steering and the brakes are harder when the rev reaches below 400 (this is when I reverse/1st gear and start to let go of clutch). Then finally it seems my car is not yet done putting a large hole in my pocket, it's guzzling gas 2 times than before. Literally. It used to go like 10km/litre now its like 6km/litre.
Can it be fixed? Is it an air problem? (My intake is kinda wrapped with tape, but I think there's no hole)
Or is this a permanent problem with my engine? Thanks in advance!