so your problem is:
1: high idle
2: high temperture while fans don't kick in
Check temp. sensors. I'm not completely shure but i read the 156 has two temp sensors - one for the gauge - one for the ECU operations - so if 2nd is dead your ECU might not notice high engine temp > no FAN.
Fiat ECU Scan could be your friend (to check the sensors).
I did a scan and no faults come up, I have AlfaDiag software
I just checked the thermo fans again
Checked the thermo fan at low speed, relay FAN 1 works fan didn't, assuming it's the large fan at the front of the radiator.
High speed fan and FAN 2 relay works perfectly during the test
Could be temp sensor perhaps, wouldn't the ecu pick that up?
Idle is mostly cause by false air between MAF and TB - or a Complete fu*ke* Throttle (... wiring problems for instance).
(The hose on the V6 for instance is a little prone to failure on the elastic part..)
You could try disconecting the MAF (this would cause a limb mode) but if the Idle get's to civilized levels after that you're close to the Error.
You could alsow remove the intake hose and have someone work the loud pedal (when engine is OFF!) to check if the Throttle is actually moving (i'm not shure but i think it won't go full open if the engine is off) - could alsow check on Fiat ECU Scan if throttle is working correct (IE not 20% open with pedal untouched)....
I think it may be the idle control valve, or a hose I forgot to connect while assembling the parts I took off.
I'll have a go at it tomorrow, don't see why cleaning the throttle body caused all this
Have to be something I did or forgot to replace