ok so after a year of dealing with this i think i have figured out the problem.
heres the deal:
October of 07
98 GSTspyder had a head gasket leak
so i decided to replace the head gasket and a bunch of other parts(water pump timing belt BS belt, etc)
had lots of problems getting all parts in to shop.
after like 2 months got everything finally together started it up and she ran funny.
reajusted timing didnt fix the problem.
the rpm's surge up and down from 500-2000
april 08
so i replace O2 sensor and IAC
didnt work replace IAC again. no fix
so no it has sat for almost 6 months and i would like to fix it before summer.

my only guess is that its my fuel pump. i have lots of surging but i cannot test it cuz of the weather. so i plan on buying a feul pressure testor and seeing what the pressure is, and seeing if it is jumping up and down(surging)
i have alot of knocks and pings every know and again so idk. any body have any other ideas?
timing is dead on checked by 3 mechanics 2 work for DSM shop and 1 for mitsu + me.
so idk whats causing this but i would like it fixed.
thanks guys for the help.

 

a vacuum leak is almost always attributed to the rolling idle problem. when i pulled my head i noticed a lot of really small vacuum lines that were not easy to find or where they went recheck those lines and make sure they are put back in the right places also check your valves you can check the fuel pump with an ohm meter . To see if it has high resistance or a voltage drop if there is a voltage drop over .5 volts from fuse to pump it has a bad connection or corroded line or high or out of spec resistance from the fuel pump would mean its bad then replace the fuel pump but really try the vacuum idea first its a gut feeling.

 

i have spent days looking over everything. vac lines all my connections i pulled everything back apart already to see if there was somethign i missed and i havnt found a thing. i probly have atleast 75 hours spent on just trying to figure out what it could be. so your saying if my fuel pump wires are corroded it could cause this problem too? i had some water get back/in the rear seat a long time ago when i left the top down. so i guess its possible. i guess i will have to wait to pull it back in the garage once the snow is gone.

any body else have any ideas on what else could cause this?

 

does it happen all the time? when the engine is cold? after its warmed up? could be the FIAV if it happens when warmed up. BISS o-ring will screw up your idle when coming to a stop. Intake manifold gasket will cause the surge (also depends on gasket medium). Also check the throttle shaft seals. They're a common boost leak location and could allow air to bypass the throttle plate resulting in high idle.

 

I really doubt your fuel pump is causing the issue, its eithera vacuum leak you cant find or the iac. X2 on the boost leak test.

 

are there any other problems with the car other than that one? Easy way to check if its a boost/vacume leak is to get a guage and hook it up... and see what the car is running/ idling at.

 

ok lets say that there is a boost leak where would i start to look. i have soent hours looking for all the vacuum lines making sure they are all in. i even pulled everything back out to make sure its all fixed/on the right way. the only other problem with the car is that the breaks stick a little(as of semptember of 08, car hasnt been drivin for almost 9 months)

the only reason i say i think its the fuel pump is cause it takes like 3 times for the car to start unless i hold down the gas pedel and then it might stay on. once its warmed up it will rev from like 500-2000 all crazy like, so it seems to me that there would be something wrong with the fuel almost as if is surging i guess.

 

you wil have to get soapy water and put pressure in the system, then spray down all areas.. It could be anywhere from the upper intercooler/lower intercooler (Common place for big leaks) to the smaller lines.. or intake manifold area..

 

ok let me ask this:
could my intercooler be leaking the boost?
could my turbo just be shot?

the only reason i ask is because i have changed the intercooler pipes to hard pipes cuz i though at one point this was my problem. but that didnt seem to really fix things any. i did notice at one point my turbo did have a lil bit of oil coming out of it, like where it would go into the intake side. but that was way before any of this really happened. not sure if the turbo is just shot and this would cause the rpms to go crazy.

thanks guys for all this help

 

Yes they an cause boost leaks, thats why you need to pressurize the system to find the leak.