bad idle possibly "idle surge"

[tunedtsitalon]

ok guys bear with me here, i purchased a whole 1991 talon for my 6 bolt swap it was wrecked but runs and engine sounds very good but there is one thing since it was sitting for 3 years and i live in pa where its 5 degrees right now it was hard to start at first but when it did stay running i was idleing up and down up and down up and down ect. you get the point . now, it is wrecked and there could have been some leaks or something im sure but if, when i drop it in my 94, it still does this what could it be ?hopefully ill update later on tonight when i get it running thnx

 

[1YLOTLN]

have you cleaned out the throttle body mass air for and/or Intake?

 

[megadeth0]

Sounds like you have the FIAV valve bypassed. There are two lines on the bottom of the throttle body that should have two coolant lines ran to them. Some people unhook them to gain a little power due to not having the coolant running through the throttle body and heating up the intake charge. In reality you don't gain much if any so I would reconnect the lines and you should be set.

 

[BOOSTJUNKIEGSX]

Could it possibly be the TPS (throttle position sensor). My car surged up and down at idle when this went bad? Just an option hope it might help..

 

[femmeDSM]

Here's a link from VFAQ that has a lot of info on idle surge: http://www.dsm.org/how-tos/tttt/tttt3.html

It's bound to be one of those things, or a combination....

I would definitely recommend cleaning the throttle body (i.e. actually removing the throttle body and cleaning both sides of the throttle plate. running Seafoam through your intake will clean one side but leave the other pretty nasty).