i've had similar problems. i've got it all fixed up now, and i can't put my finger on one thing that fixed it. i kinda did a lot of stuff at once and it got WAY better. but what i did was cleaned the line that connects to the balance tube. there are two idle control components back here. i took the hose off and sprayed wd-40 down it with the little want attachment. then i disconnected the other end, and did it from that end too. this brought my idle down about 300 rpm. since then, i have replaced both components that are in line with that hose. i did as suggested already and tested the TPS. mine was bad. i replaced it. i cleaned the throttle bodies too. scrubbed the butterflies well. did some other things too but it's late and i can't remember
