Various engine problems

[Darkmood]

Ok, so this all started last night. Car is running rich, engine idle has dropped from 750 to 400, engine is missing, stumbling and will stall out if left running or clutch is depressed. Also vacuum is running about 4 psi lower than normal it was at about -9psi and is now at -4psi. Mods in profile. Any help is greatly appreciated.

 

[98mitsuGSX-SD]

First off, I'd suspect ignition problems. The fact that it's missing and still getting fuel from running rich. The loss of vaccum is probably due to the cylinders aren't getting spark and not creating the proper level of vaccum. Check your plugs, wires, coils, power transistor, and CAS.

 

[architechnik]

Is there a duck/bird in your air intake?
It sounds like there isn't the right amount of air or the O2 sensor is sending the wrong signal. When was the last time it was checked?

 

[Darkmood]

Last time I checked the intake was about a week and half ago. I'll definitely check all the stuff again though.

 

[NATAS]

Did you boost leak test it? Unmetered air will definitely cause the symptoms you're describing. I blew my UICP off my TB elbow just a little bit and it wasn't enough to make the car undriveable, but it did run like ass and sound like it was missing and it made no boost. Stuck it back on and everything was perfect. MAF cars ftl!

 

[Darkmood]

Well, turns out my alternator had died. Put a new one on and it runs like a dream now.