Okay,i'm going insane here.87 TA 5.0 TPI (5spd) has a issue with idling.It bucks below 1200 rpm when taking off,and keeps getting stuck on a higher idol..The colder the air temp,the worst it does it(both)...If it's stuck on higher idol when i come to stop,it will come down to 450-500 after about 10-15 seconds.Sometimes it don't though.Usually sticks at 1500-to 1800rpm.Not constant,off and on,but enough to annoy the **** out of me.So i figure it has to have something to do with the bucking too.The IAC was replaced last year by previous owner..Was told it ran great for most of the summer after that,then started actng up with the idling..The TPS is at 56..No codes have ever come up,but the service soon engine light a couple times...Any ideas,anyone?? Also,the canister has one line still goin to gas tank,one to throttlebody(i believe),but the control valve is not hooked up.There is a plastic hose that goes over by the antifreeze resivor,but not hooked up.The other end goes to a tee,that hooks under the throttlebody.Then runs to the pass-side near dist.In a rubber plug of some sort,and the other line coming out of that same rubber peice goes to EGR.Does the plastic hose by resivor go to that canister control valve??? Any help would be so appreciated..

Thank You