DUI is a criminal charge in the US.
for the OP, if you have applied for a pardon, your passport will be flagged and you will be denied entry to the US.
You should avoid this trip, if you are denied during your pardon application process, you will be denied after the pardon has been issued as you attempted to enter the US when you knew you had charges that would not make you ineligible for entry.
ANY drug charges are taken VERY seriously.
Take his advice, buddy of mine just got denied entry into US for Vegas trip. charge was 22 years ago.