Rough idle when rpms are low. The idle jumps up as it gets low and now it will just stall as it gets low. I have checked all vacuum hoses and there is one that is disconnected but I can seem to find where is connects to or if that is even the issue. I will attach video/picture. The hose comes from the firewall and comes out underneath the passenger side of the car.

 

what car do you have? any check engine lights?
that hose is likely just the A/C condensate drain which is normally open to let water out.

 

its a 98 gs 400. the check engine light will flash if I try to move the car, otherwise it wasn't on at all

 

Scan the car.

If you have a flashing CEL that's a dead miss condition so one or more cylinders aren't firing at all and you need to figure out where the(y) are to begin looking into the issue.

 

Confirmed. thats the A/C drain hose, normal condition.
You have to scan the ECU via the OBD2 port for codes, a flashing MIL light is a servere malfunction.

 

I spent hundreds of dollars trying to fix a rough idle. No luck.

Then I added a 20 dollar fuel cleaner to my gas tank and it fixed it immediately.

 

Anytime you have a flashing CEL, u need to park it, and scan it to see what codes are being generated. That will make it much easier to diagnose the problem and help with the best solution. Do u have a scanner? If not u can borrow one from AutoZone if u leave a deposit. Scan it and then post the codes here and we’ll go from there. These engines are really solid, it’s likely you just have a wiring problem or something like that. So don’t panic