Recently picked up a 05 mustang, 4.0, automatic, with zero known history. When I went to look at car it was idling a bit rough but was throwing code for EGR valve, it would smooth out and run fine at around 1500-2000 RPM's. Car was delivered 3 days later. We replaced the EGR, radiator and water pump, code was cleared. Car now will not start unless gas pedal is all the way to floor, and itll die as soon as you let RPM's drop below 1500-2000. It will still run smooth as long as rpms are up. It's making a fairly loud knocking sound that's coming from the intake, you can put your hand everywhere under hood and don't feel the knocking until you put hand on the left side midway back of intake. The knocking isn't quite as loud as a rod knocking in motor would be. We checked for vacuum leaks and didn't detect any. And its throwing the EGR code again. It also threw the code for CBDII port incomplete. Any thoughts???