Runs better w/out MAS plugged...why?

[unlikely hero]

Well yesterday I started my car and at first it wouldn't idle or drive. It would just buck pretty badly even under full throttle. Well after it warmed up she drove like normal. Well today same thing but it won't go away. I mean this is undrivable because even if I pump the gas I just get really bad bucking. Well I unplug the MAS and she drives fine other than the high idle and shitty gas milage. So whats the problem? Bad mas? Would it go out all of a sudden like this. Also anyway I could tune w/out a plugged in MAS w/ my sAFC because I'm going on a 800 mile trip in 4th(trannys bad) and the gas milage is just going to kill me. Also know its idling like crap I mean I can hear the misfiring and if I rev it she'll pop once in a while. I think thats prob just my exhaust leak.
I know this isn't the reason:no boost leaks, I'm boosting just fine, good idle vacum, new spark plugs correctly gapped, anyhow I would have the same prob w/ the unplugged mas. So what could this be?
=Jason-

 

[BOBS90TURBO]

I had the same problem on my first turbo dsm a couple of years ago, it ended up being a bad ecu. See if it smells like a crapy fishy smell or look for burns on the board.

 

[eclipse90gsxt]

Its probably the mas is bad, if the car runs when the mas is not connected.

 

[Dallas J]

Your MAS is probably bad and sending some wacky signals to the ECU. When you unplug it the ECU will just go off of what its preset values. My MAS went bad when I first got my car and the only way I could drive it was to reset the computer and unplug the mas.

-Dallas J