95 gst(needle bounces down then goes back up on start up)

[gameover95]

Hey guys quick question.

My 1995 Gs-t when you first start it the rpms drop like it's going to die but it goes back up quickly. Idles perfect after that only a little bouncing. However, sometimes after you start it and it drops itll just start bouncing like it wants to die but if you give it a little gas and let off it'll idle perfect. Garages seem not to know anything everytime I ask. Engine is fairly new..about 6k on it same with the trans and clutch. This started happening after the FMIC was replaced and new piping was put in with the new BOV. Just want to fix the start up issue..also makes the belt squeal when it drops down and goes up..(started happening after the crank pulley and alt belt were replaced).

Any help is much appreciated..please be detailed questions/answers..

 

[chronicvex]

I have same issue but only happens on warm starts.

 

[gameover95]

I have same issue but only happens on warm starts.

Yeah same here, on cold starts it idles high enough

 

[moronthr33]

Have you tried a boost leak test

Also you said you replaced you belts? Check to make sure their tight I've seen cars act wacky if the alt belt isn't tight enough.