Over fueling problems in golf mk3

hi i have have a 1992 mk3 golf cl 1.4 and i am getting strong petrol fumes coming through the vents when the veh idle.The veh also is very slow and slugish to accelerate (especially up hills) on lower gears. I have taken it to a mechanic who adv that it seems like it is using more petrol than it should he had replaced the temp switch (du to wrong ECU readings) which has cured part of the problem but i am still having the same problems can any one help?

Does the exhaust sound funny, like a clogged catalytic converter?