idle help

i have an 86 b2000 some times it idles high and some times it doesnt idle. i tried using the idle screw but it wont bring it down any just goes up. any suggestion?

anyhelp would be greatly apperciatie

thanks,
brennan

lube every thing....really good start there
all linkage

mine idled really high at first and it was the little device on the carb that stops it stalling when you take your foot off the pedal too quickly, the little pressure pot on the front end of the carb.
I also just lubed my linkages and that helps it too, I used, spray on white lithium grease, it costs more but it's well worth it.
Just spray anything that turns when the cable is pulled and that should help also.