Hi,
At 18V, the setup pulls 134mA when idle and 145mA when ringing.
At 20V, it pulls 122mA when idle and 122mA when ringing (except it doesn't).
Why does it pull current when idle.
Please define idle.
What is the total DC resistance of the coils?
What current is your lab supply rated at?
You have got the current limit turned up?
What are you doing with the EN pin of the 298?
Connect it to 5V, rather than leave it open circuit.
Can you please post a picture(s) of your project?
Thanks.. Tom... 
