anybody got any good ideas for cleaning out the air ducts in my 88 f150, seems as if everytime i turn the heater on high i start sneezing, not sure if its allergens or just dust, bit it is getting really annoying...

 

I heard NAPA has a cool kit for doing just this

 

There are kits for this but on a 21 yo vehicle they will work marginally at best. It's likely that the evaporator core (assuming factory AC) and case are full of dust, dirt, debris and mold. The only real way to clean it out is to pull it out and disassemble it.
You can get to a good bit of it by pulling the blower motor and flushing out as much as you can with soapy water and Lysol.