My check engine light has been on for years and I've replaced the Oxygen sensor but the CEL stayed on. Ive been doing lots of online research and some people seem to think it might be the EGR or DPFE sensor. I've located the EGR but it will be a bear to get to because it's under the intake manifold but I can't find anything that looks like a DPFE sensor and my Haynes manual doesn't mention the DPFE at all. Can anyone tell me:

1. Does the '93 Ford F-150 have a DPFE sensor and if so, where is it?

2. Any hints on how to remove the EGR sensor without removing the intake manifold (EFI model)?

3. Any hints as to what might be causing the CEL to stay on aside from these two items (02 sensor and EGR/DPFE)?

I will sincerely appreciate any help rendered. Thanks very much.