when was the car tune up done ? it can also be a computer problem that the computer sensing not enough fuel so its causing more fuel to be injected into the cylinders. check the entire fuel system and see if there are any leaks.
Thats very sick of Juma al Majid to ignore you and your problem for so long. Replacing all 4 tires isnt big deal as when car only vibrate as some specified speed this clearly mean that some tire isnt balanced properly or may have a swollen tire which again is tire manufacturing defect.