hello, ok we got a car in the shop that started from boxes, we got in running finally, but when we floor it the car will miss. then the dme shuts down that cylinder. it will not miss at idle or part throttle driving. i have driven it about 5 miles with light acceleration and no problems, then i floored it and it started missing in random cylinders. sometimes in cylinder 2 and 4 and sometimes in 3 , not very often in cylinder 1.
these are the thinks i have done or checked, it has new plugs, plug wires, coil pack, new injectors, new throttle body all oem, i have drained all the fuel out of the tank and put 1/4 of 93 octane good new gas.
i have checked timing by taking of the valve cover and checked the cam. ok, when the car came to us they said they pulled the head and performed a valve job, but i did check compression, even in all cylinders at 180, performed leakdown and found 6 percent, 10 percent, 8 percent, 8 percent, i have also unplugged the o2 sensor , no change, un plugged the boost sensors, no change, unplugged the cam sensor no change. i have tried factory jcw progamming and no differnence, a side not that one day i just hopped in the car cold and took off and it ran like a bat out hell, no problem until i got to a stop light and it sat there it was fine then i punched it again and started to break up again.
the car does have a aftermarket bigger intercooler, a super charger pulley not sure size and a crank pulley not sure size, but the belt size is a jcw size belt for reference, it has has the dme tuned with 3 tunes, original , 1 and 2 , it doesnt have a name on the programmer hand held device so i dont know brand. thanks for all the help if somebody else has has same problems,

 

My thoughts are fuel pressure issues, bypass valve, or vacuum leak.

 

I had a semi-similar issue and it turned out to be the vacuum line under the left side intercooler horn had popped off. I would check there, it is hard to see and easy to miss though