I replaced the mass air flow sensor and the idle air control valve and my check engine light is still coming on with the code p1506 which is saying malfunction with the idle air control valve which is new what could be the problem now and its not a defective part I have had three different valves and the light has came on after driving about 30 minutes each time

Check for vacuum leaks. You can often get these codes from something as simple as that.

Well my check engine lightkeeps coming back on after I erase it with. The code p1506 I have replaced the mass air flow sensor and idle air conrol valve I have put it on a smoke machine to check for vacuum leaks. And had the idle air control valve and connector checkex and everything checked good. The codes readeris saying idle air contol malfunction speed control what could it be