Ok so I'm having issues.... I have a 2003 A4 Quatrro. The car is hard to start only when hot, 10-12 revolutions before it kind of sputters to life. On a cold start the car sounds like it has a exhaust leak.. that goes away once it warms up. Once running the car develops almost no boost. 2lbs tops at WOT. The car wont rev past 5k either. Feels like the car is in a soft limp mode. I have pulled codes, they are as follows
PO300 RANDOM MISFIRES-
PO303 CYL 3 MISFIRE
PO302 CYL 2 MISFIRE
PO299 TURBO BOOST SENSOR/ UNDERBOOST
PO501 ENGINE SPEED SENSOR
I have replaces all 4 coil packs (OEM) and spark plugs
I have replaced the DV
I have replaced the engine speed sensor (not oem, is that bad?)

Any feedback would be great thanks