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Trim system lean... I have no idea what that means, but it sounds like the pcm has exceeded it's fueling limit, and it's still detecting a lean condition?

Did this just happen suddenly? Surging idle can be a result of an overly lean condition, I would suggest changing the fuel filter before anything else. One bad tank of gas is all it takes to plug one up.

A surging idle with a fluctuating fuel pressure is kind of a catch-22. They both could cause each other.

If after the fuel filter change, it doesn't get better, you can probably suspect the fuel pressure regulator.
 

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mcowden said:
Eldorado1, I think the code is telling us that the PCM has leaned out (trimmed) the mix as much as it can.
Well if that's the case, then yeah, it's definately the fuel pressure regulator. It could also be the vacuum line to the regulator got disconnected. That would send the max pressure to the fuel system.
 
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