If combined with HC and CO levels well under the limit, high NOx generally means the engine is running too lean. High on all 3, probably the catalytic converter is worn out.
If you want to try some alcohol in the tank just use E85 (sold at gas stations, 85% ethanol and 15% gasoline, works in "flex fuel" cars) if available in your area. It is much cheaper than anything else. Heet is basically alcohol, though it may be methyl or isopropyl instead of ethyl. Ethyl alcohol is the base for E85 and denatured alcohol.
I have no idea though if alcohol will reduce NOx emission. Use too much and your car will run very badly. Nearly all the gasoline sold now starts at 8 or 10% ethanol so you need to blend in at least that much to change anything (i.e. one bottle of Heet in a gallon of gas isn't a significant amount.)