Welcome to the club!!
The reason for the dieseling is run on due to maybe some carbon buildup in the combustion chamber and/or idle set alittle too high. Idle speed for a manual with A/C on is 500 rpm. Auto trans w/A/C on is 600 rpm.
First thing I would do would be to leave the trans in gear and stop the engine under load.
Secondly, go to a reputable dealer or parts house and purchase a can of BG 44K and add it to the tank right before fill-up.
Thirdly, if it still does it, run a pint or so of water through the carb while maintaining good engine speed. Pour in water lightly so as not to drown it, but, enough to do some cleaning. Water turns into steam, steam removes the carbon from the combustion chamber, engines does tend to run alittle better.
Hope the above works, maybe others here will chime in with their suggestions....
Everett "OBJECTS IN THE MIRROR APPEAR QUICKLY UPON RAPID DECELERATION"