1986 toyota pickup burns oil at stop lights

i have a 1986 toyota pickup 4 cyl turbo with 165000 miles, its also automatic. the truck seems to burn oil only when stopped at a stop sign, although it does sometime burn while driving but not nearly as bad as when i am stopped. it also seems that if i put it in park or neutral at lights it doesnt burn oil as bad. could it be a vacum line mix up, any ideas.... thank you