Lower intake gaskets - 4.0 OHV

[masospaghetti]

Working on curing three CEL's - EGR insufficient flow and P0171 and P0174 (lean banks 1 and 2) condition. I found the culprit for the EGR code. The DPFE leads for the hoses were broken apart, brittle from the heat I assume. Questions for ya'll:

1. I know the upper plenum gaskets can cause this, but how about the lower plenum gaskets, or even the lower intake manifold gaskets? Should all of them be replaced?

2. Anything else I should do while I have things apart? I just bought this truck, and I want it to last a long time. Cam synchronizer? Fuel pressure regulator?

3. How does the EGR tube remove from the plenum? I would like to replace that O-ring in there.

thanks all - 98 Explorer XLT, 5-speed. 200k miles.

 

[swetrid]

There are fuel rail gaskets between upper and lower intake that get sucked in and cause lean codes also.

 

[rocket22]

fel pro gasket kit

will have the gaskets for all, (I didnt open my fuel rail). My EGR tube basically rusted away, so be careful when disconnecting and moving. I put a polug in the EGR tube and truck runs fine!