The EHC is a small rectangular black box mounted on the rear side of the airflow sensor. You will need to remove the air cleaner to see it. The EHC has a plug with 2 wires that can be unplugged for testing. Do not remove the entire EHC because it contains pressurized fuel.

EHC's can go bad, symptoms are leaking fuel and cold running problems. However, there are many other things that can cause the "bag of spanners" (I love that) problem you describe and I would check other engine control inputs first, such as the coolant temperature sensor.

Good Luck....