If it's only doing it at part trottle, it could be that it's running too lean. As a rule of thumb you should not be running high boost at part trottle. Check to see how high your boost is at part trotle when it cuts out. I bet is well above 10 psi wich is about as far as you want to go safely at PT. Now if you have a speed density system and it's properly mapped, then you don't have to worry about anything and you wouldn't have this problem.
I've had this situation some years back on one of my cars, drove me nuts untill I learned the way the computer worked and what it was doing at PT.

Alex...

 

This sounds a little bit like a problem I had with my car a few times. However, my car cut out while I was slowing down. I pushed in the clutch and the revs went crazy...got the shake...then the car died. The SES light came on so I took it into the dealership. They couldn't figure it out (the errors that popped the SES were off the board nuts [Crank & Cam failures at the exact same moment] & did not come back after an ECU reset). It happened two more times with big breaks of a couple of months in between...

I talked to some mechanic friends and the first thing they said was "Do you have a hydraulic clutch? If so it sounds like a problem with the sylenoid." So checked the general area and surely enough there were two layers of dried fluid on the clutch line leading from the resvoir. I pointed this out to the dealership, but they assumed it was from when someone refilled it. However you will note one that it happened twice and I am 99% sure that they never filled it once let alone twice. Second the resvoir has a system the protects it from spilling even while filling.

The only thing that I can think could be causing the fluid rush back is that damn clutch line. I plan on switching out the clutch, flywheel, and all here shortly with an OS Giken clutch & tranny protection system so that my car does not suffer due to some re-used bad idea by Mitsu...

Bottom line check your fluid level in your resvoir & check for leaks along the line. Basicly it appears that a build up in pressure for whatever reason causes the fluid to come out & I assume if its doing that then it could damage the line or anything along it and cause more severe leakage...

Just my 2 cents...good luck to you all...