suprababy

Got an 2001 is300 srt stage 2.75 .it is running rich,got code for intermitent missfire,code for insuficient coolant temperature for closed loop .Tuner couldn't do anything because he said the ecu is not conectiing anyways what i did : temp sensor replaced,thermostat,spark plugs,wideband . It is still runnig rich
what else can cause me runnig rich,why me code stay for insuficient closed loop .The Ecu already was inspected my haltech and they say works perfect
Haltech F10X