another idle surge problem

[ryanallan]

here is my story;
for the longest time i have had an idle surge problem (about 2 years ago now my idle just droped to 500rpm and never came back). only after boosting will my idle start to surge at 2000rpm. after some easy driving the idle usuay drops back down to around 1000rpm. and for the longest time i had thought this was a ISC problem and was actualy going to replace this part soon (pocket logger some times reads the ISC as zero and other days it will read between 20 -30).
however today after some boosting my idle again is up to 2000rpm and wont come back down.
now when my car decides to idel at 1000rpm, i can get a full 24in/lbs vacume but when it decides to idle at 2000rpm i am only able to get 20in/lbs... so im not so sure its a ISC problem any more.
I figure when ever i boost i blow some thing open (EGR, BOV, turbo seal... etc) and as time goes on the leak seals its self and my idle goes back down to 1000rpm.

so any thoughts ?
ps. i have been searching for the past 2 years and have yet to come across a problem like this

 

[fun-flyer]

dont know if this will help but,my car used to surge up and down,up and down at idle.
problem was that the temp sensor crapped out.this senser far as im lead to believe lets the car know when its at operating tempture to give proper fuel flow,gives more fuel when cold,less when warm,when its failed the car dont know what to do,as in more or less fuel which causes the surging.this was on on old subarau,same thing im guessing on any car.i replaced with a used one problem solved.hope this helps

 

[ryanallan]

thanks for the suggestion, ill add the temp sensor to my list of things to check.