Mitsubishi Repair: vibration from front wheels, mitsubishi galant vrg, mitsubishi galant

Question
My 1997 mitsubishi galant vrg gdi,1.8l with 4G93 engine semi auto has got a number of problems.I have suffered with these problems for quite a while to no avail.Howver the issues are itemised below:

1.The engine tends to have a rough idle and rarely but occassionally goes off-But i have read in this very forum that it might be the idle stepper motor so im gona check that out this weekend

2.It gazzles fuel like a problem(1L for 6kms)and has a hard start after along stop or in the mornings.The engine runs fine without smoke however there is a high carbon(soot) build up in the exhaust lining and spark plugs.I had the engine overhauled sometime back during which a great carbon buildup on the pistons could be observed.Engine was cleaned, piston rings  and overhead gasket replaced however there was no change at all in performance. Can anyone provide a solution to this prob.

3.The car tends to vibrate at the front wheels when cruising at about 40km/hr,the vibration can even be felt on the dashboard however it disapears at about 60km/hr. What could be causing this

4.I need to find a repair manual for this car. I have checked many sites that claim to have this manual but all i see is manuals for other galant models. I need one for A GDI GALANT VRG 1.8L SEMI AUTO. If anybody has one, soft copy or hardcopy even knows where i can buy one i would be greatful.

5.Im also looking any vendor that deals in spare parts for mitsubishi galant vrg gdi 1.8L. In my country(Uganda) its almost impossible to get parts.Any help

Answer
George,
Your performance and excessive fuel usage may be interrelated.  You may have a bad O2 sensor or other failing emissions component.  This will greatly reduce your fuel economy, cause excessive carbon build-up in the exhaust and plugs, and reduce the engines performance.

Heavy vibrations are most commonly caused by unbalanced tires.  Misalignment and worn suspension components can also contribute to this issue.  A potential, though less common, problem could be warped steel belts in the tires.  
Good luck!