In an ideal world you would tune the HSN first then the low, BUT sometimes its nescessary to lean out the LSN a little first to get it to pull off cleanly. Don't lean the bottom too much though until you have tuned the HSN, just enough that it doesn't stall.
As far as the car creeping forward is concerned have you tried the trim on the radio? (I know it sounds silly but I have to ask) If you haven't you might want to turn the trim on the throttle down a notch. There are other things it could be but its intriguing that it stops when you switch off the tranny.