So I finally test drove my car after the swap, before at start up I would keep my foot on the throtle for a min till is idle on its own. I thought this is some what normal since I removed all emmisions and including the BAC. it idled some what rough but after 3.5k or so rpm the engine sounds normal. when driving it it did not had any power at all, I had to shift at 4k rpm instead of normal driving at 3. It stalled really easy and noticed if I pumped the brake pedal a few times I would stall too.
Any one know what can cause stalling when pressing the brake pedal?

 

List, in detail, everything you did to convert the car to accept an S5 engine.

S5 TII EM harness or S4 NA?
If an S5 EM harness, list all the wiring changes you made, at the front harness in particular.

Full S5 keg and electronics or S5 keg with S4 TII electronics?

 

S5---> engine, upper and lower intake manifolds, turbo.
S4 T2--->ECU, Boost sensor, MAF, Throtle Body
S4 N/A-->EM harness, I simply extended the three wires for the tps. I removed the emissions.
S5 T2 --> coolant sensor, Intake Air Temperature sensor, Crank Angle sensor.
Air control valve, BAC, and Oil metering pump have been blocked off. Im Premixing.

 

have you boost leak checked it? new plugs and wires yet? where is the pressure sensor hooked up to?

 

Ok, so it's essentially an S4 to S4 swap. Probably not any swap-related electrical gremlins to chase down.

Possibly a vacuum leak big enough to rob power under load and ruin the idle.

You could also try pulling engine codes, test the boost sensor & test the AFM.

You may even swap in your old NA AFM to see if it idles at all (but don't drive it under boost). I know I have an extra (bad) AFM that will completely mess up the mixture to the point where the engine runs rough / won't idle.

 

the boost sensor is connected to the nipple thats just next to the BAC. yes I checked for boost leaks and the only place I could think off is a bad check valve in the booster