Eddy 1407

I've experienced similar issues when plugged into the wrong port...produced a 400 rpm drop when going from park or neutral to any directional gear, accompanied by a healthy thump in the driveline...when I just disconnected the vacuum advanced the drop was closer to about 100 or so and much less drama when going into gear...with a 600 cfm Edelbrock on a stock 5.2 magnum.