I just purchased a rebuilt 4.0 from Quadratec, finally finished installing it and now it is showing the following codes:P0353,PO0352,P0351P0155 says intermitten loss of camshaft position sensor or crankshaft position sensor. I put a new O2 sensor in it, it said bank 2 sensor 1. I replace the one closest to the firewall on top, before the cat. It does skip every now and then when driving it. I have not noted the details. The ck engine light seems to flash 5 or 6 times every now and then. I have read alot of posts but they seem to be leaning towards the TSB about valve issues and carbon build up. Any ideas seeing that this is a fresh motor? It did say some other code about a leak with the EVAP system or something but, it has not come back recently.