Future

I am Losing power in 3rd gear at about 3500rpm only when I am stepping on it. I also lose power random whenever i step on it. Here are the vagcom codes
5 Faults Found:

17865 - Exhaust Gas Temp Sensor 2 (G236)
P1457 - 35-00 - Open or Short to Plus
16815 - Warm Up Catalyst; Bank 2
P0431 - 35-00 - Efficiency Below Threshold
16805 - Warm Up Catalyst; Bank 1
P0421 - 35-00 - Efficiency Below Threshold
16487 - Mass Air Flow Sensor (G70)
P0103 - 35-10 - Signal too High - Intermittent
17963 - Charge Pressure
P1555 - 35-10 - Maximum Limit Exceeded - Intermittent

I have a apr stealth catback and a awe b5 s4 downpipe cut and modified for my C5. I also have a b5 vast performance intake with heat shield. Giac chip

GTA_Driver

Test for boost leak, or a faulty N75 valve.

eejimm

EGT sensor failure like the code shows will put the ECU into limp mode, making the mixture rich and limiting boost. This is a common failure - the solder joints inside the EGT electronics box come loose or short out. You can open the box up and re-solder the connections, or (what most people do) just replace the unit.
Jim

GTA_Driver

EGT failed on only one bank, and from what I understand, the loss of power and drivability will not be as dramatic when EGT fails as is described by the OP.

2.7Lturbo

could be multiple issues. you can test the EGT with vag-com to rule it out