"Pending" P030X codes, occasional engine misfire

[jfoj]

Rookie,

I am somewhat at a loss for the moment, nothing really standing out. There is an obvious Lean condition, but what came first the chicken or the egg??

So is the Lean condition a true Lean condition or is this due to Misfire with Fuel Cut off and is one or more cylinders pumping a lot of air/oxygen into the exhaust stream??

Shooting from the hip here, what is the status of the fuel pump relay? If it is original, I would replace it. Not 100% if the E53 horn and fuel pump relay are the same, if they are, swap them and see what happens.

I am tied up the rest of the day, will think about this and look over again in the next few days.

[Rookie48]

JFOJ:

Swapped the relays a week or so ago, actually replaced the fuel pump relay with a brand new relay today. No change.

Also replaced the idle control valve, no change.

Removed and bench-tested the secondary air valve, it is working properly and had little to no carbon build-up.

Connected a fuel pressure gauge, secured it to the windshield, took it out for a test drive. Pressure never bobbled or moved off of 45 psi.

Drove home from the shop and again it threw misfire codes (all cylinders) and entered limp mode twice on the highway (above 75 MPH), and unusually it didi it in first gear going down a short hill into my driveway.

at my wits end on this one.