98 Windstar strange finding

I have a 98 Windstar that runs poorly at idle and will stumble at higher speeds. Every once in a while, the car will not start, but if I retry the next day it will. I purchased an ELM327 OBD scanner to try and determine the cause even though error codes were not coming up. I noticed whenever I plugged the cable into the J1962 connector on the car(just the cable-no electronics), the car quit stumbling and every time I plugged the connector in when it would not start, it started with no problems. If I unplugged the cable immediately after a successful start and tried restarting, it would not start up. Any suggestions?

On most vehicles the obd port is on the same power as one of your cig lighters. Are they working fine?

Try wiggle test, see if it changes the way it runs when it's stumbling. I think you may have a short somewhere.

Thanks for the tip. I tried it but it did not seem to effect the problem.
I found the rough idle to be an IMRC problem. However, the car still seems to be dependent on the straight through cable plugged into the J1962 plug. I called the manufacturer of the cable and he stated the cable had only wiring between the plugs without any cicuitry built into the plug.