(T) Fiat Strada 1.6 16v misfire at idle.

Hi! I recently bought a 2009 Fiat Strada 1.6 16v with 142 000km on the clock. It had a misfire at idle when I bought it and it will sometime stall when you come to a halt. The car pulls well in higher revs,but has an issue at idle. No engine light or fault codes. I recently had the cambelt replaced for safety,new spark plugs, all filters and oil replaced. Misfire is still there,still smells very rich. Also replaced the idle control valve on the throttle body,and today they replaced the lambda sensor as the wires touched the exhaust and the insulation melted. Diagnostics done before and after. Lambda now reads on diagnostic machine,but no change in idle or rich running. They also checked the intake for air leaks with a special smoke machine,no air leaks. Someone said these cars are prone to injector failure... Please help?

I have the same problem, already replaced throttle body, coil pack, HT leads, O2 sensor. Done compression test, all fine. Still not running smooth. Please let me know of further developments.