well i havent had the truck long, the past month i been driving it everyday, its a 88 4x4 with the 2.9 seems to run really nice, starts right up everytime. but lately when i hit a stop light and clutch it will idle up and down it doesnt do it all the time but alot i guess, sometimes if i let it do it , it dies, but fires right back up. if i give it some gas it snaps out of it usually. any ideaS?