I just installed a rebuilt 20v head, water pump, all tension rollers along with the usual gaskets and so on. On my `03 VW NB 1.8 Turbo. Now it has a misfire at low r's idles rough and reads a p0171 and a p0016 that's the only codes I get. I've checked the usual vacuum leaks any suggestions? I bought this car with the top end torn down so I don't know if it's an ongoing problem.