Buy an Innova scanner or go to Autozone. You may not be throwing a code but that scanner will give you a yellow light if an emission part is working but is going bad. As always the MAF should be cleaned and check your plugs but your tranny would be a bad omen. Worse case take it to a dealer and have them check it out. At least get a qoute and that is for free. As long as there is no CEL then the qoute should be for free. If you have a CEL then it cost to just have them hook it up to the Star machine!!!!!!!!!!!!