happens to me, but doesnt stick all the time and only stays around 1600-2000 rpm rarely.

 

well i got an 89 4wd and mine sticks alot
then one day it didnt run too well and well now i have low compression in one cylinder....thats another story

BUT.. i did take my throttle body off and there seemed to be alot of gunk created in there
after i cleaned that out it was much better

but i got other problems with mine