jspringator wrote:
What is a DEPF and how do I check it?
It's basically the EGR pressure sensor. Usually it will set EGR codes when it starts failing. I don't believe its a common problem.
With a problem you are describing, it may take a long time to diagnose without the proper equipment. The most useful test at this point would be a "cylinder contribution" test. This requires the Ford IDS shop computer, or something equivalent like Snap-On Modus or AutoIngenuity. This will show which cylinder(s) are weak. At that point, individual can be tested. Injectors are easy because they can be turned off individually. All dealers and some independent shops also have a COP tester, that way you aren't just replacing good parts. That said.... if you have aftermarket coils.... I'd be awfully suspicious of those.
