Okay guys I got a stumper for ya! The patient is a '90 Talon TSI 2WD. About a month ago, the car began having a problem running. She would start, idle about 2K for 10 seconds, and then idle real rough until she died.

Had it towed to Mitsubishi and was told it was the gaskets for the intake and the fuel injectors and they wanted 800+ to do the work so my cousin and I said hell with that, and did it ourselves. While we were at it, we remove the Air conditioner from the block, and cut the hose that ran to it. Had very little problems but even with new gaskets, she does the same thing. Will run ok for about 10 sec then she will spit and sputter to death. She has an aftermarket boost guage and we arent reading any bosst on either that guage or the stocker boost guage. I didn't know if a vacum leak could cause this much trouble, but as far as we can tell, everything is run where it needs to be, or is properly capped off. I wanted a 10 sec car, but not one that only runs for 10 seconds. Help guys!!

To me this doesn't sound like a mechanical problem. If the car runs fine for the first 10 seconds all the hardware is fine. A vaccuum leak won't cause it to sputter and dye unless there is enough air getting into the cumbustion chamber to make the fuel charge unburnable. (Not likely) Ok since I don't know what all you have already done I'll throw out some basic things to check if you haven't already.

Plenty of fresh fuel?
Maintained fuel pressure?
Clear fuel filter?
ECU ok?
Coolant temperature sensors plugged in and working properly? (One of these sensors tells the ECU when the engine is warm which effects how much fuel is delivered)

Hope some of these suggestions can lead you in the right direction. Post up on your progress or more questions.

I would look at the ECU. sounds like an ECU on it's way out.

yea definetly check the coolant temp sensor but usually they go out and make it hard to even get the car started.... Marcus nailed it tho by mentioning all the above issues... Sounds like she is starving of fuel after it gets started up.... Although with these cars you could have a headlight problem and it be related to the ECU....

Obviously if you have a spare ECU to try, that's the way to go. However I'd still check your vacuum lines real well, that could cause an idle surge on start, and then the ECU would try to compenstate

She has an aftermarket boost guage and we arent reading any bosst on either that guage or the stocker boost guage.

Id start there. Check for leaks on the boost/vacume side first. Easy check really. Is the hose blown off at the intercooler? Sometimes it looks like its on, and its really not. If you are not seeing boost, or vacuum on either gauge, Id say thats a sure fire way to get a car to run like butt... (keeping in mind the oem is electrical and not mechanical). Your aftermarket one should be reading in the vacuum range at idle even for 10 seconds.