Long story short I've been chasing an intermittent misfire for some time now and I was pulling apart my IM and EGR to re-clean and replace gaskets since I reused them last time and its been bothering me. But when I pulled the upper manifold off, my VICS butterflies were wide open.

I've searched around but can't find any info on this happening to others. Any ideas why it would be stuck open? The actuator moves pretty easily by hand. Failed solenoid? Do they usually fail open? Am I an idiot and they are always open when the car has no power( although I feel like i would remember that from a few month ago when I first took it apart)?
Could this have any relation to my misfires?

Its a stock 99 I've already replaced coils, plugs, wires, and the majority of the vacuum lines now I'm moving towards fuel related stuff starting with the fuel filter but no luck yet. It typically only happens after about an hour or so of driving so I'm at a loss. I'm mostly concerned with the VICS right now since my manifold is apart but help on any front would be greatly appreciated. thank you!

 

I've worked on a miata that had sticky VICS butterflies. I manually activated them over and over until they loosened up and the actuator could actually control them.

but easy enough to test your solenoid/actuator... also check the check valve on your vacuum reservoir.

 

I'm quite certain that they normally sit open until the solenoid is activated which closes them. At least every time I've taken the top of the manifold off they have been open, and I'm sure mine are working properly. Either way it should not have an effect on your misfire issue.

 

Well that's some peace of mind anyway. How would I go about checking it. It's activated by vacuum pressure and the plug by the egr valve right?

Where is the check valve located?