The replacement ECM arrived today. So I "dodeca-checked" all of the wiring under the driver's side dash, the passenger floor board & ECM harness, to include ground points, and even poked a look at the cam position sensor and O2 sensors (didn't remove, just checked wires for integrity). Then, with batteries disconnected, I swapped out the ECM. It started without stalling, but would bog down when I touched the throttle. I think that was partly-due to the ECM testing the system and adjusting. The engine "loped" a bit at first, but seemed to smooth out after having some run-time. I kept checking and clearing the pending codes. The first set was the same: misfires and internal RAM error. But it was running. So I had a feeling that the old ECM was part of the problem. But it isn't the only problem.

Once the engine smoothed out and responded to the throttle without bogging, I took it for a test-drive and checked/cleared the pending codes a few times. The first codes were misfires, but no RAM error. A few minutes later, the engine felt gutless - more so than I have experienced before. I checked for codes and found P0171: system too lean, but no misfires or RAM error. I have been getting the P0171 code off and on for the past year. It could be a leak in the intake behind the MAF (first appeared after I changed plugs, coils and wires). But I'm also wondering if it could be a bad O2 sensor... maybe both? Anyway, the engine idle immediately-returned to a "minor lope" when the code cleared. And the engine was much more responsive. So I'm wondering if the "system lean" error is causing the ECM to make the engine run too rich. Possible?

That noted, here's my plan of attack...

- I'm going to pull the throttle body and reseal everything that was removed when I did the tune up. I'm also going to remove the Spectre air filter (cone-type) that I installed at the same time I did the tune up (it came with the vehicle, but was removed by the previous owner so the vehicle would pass smog). I'll re-install the factory air box with K&N filter (that's how it was running prior to the tune up, which was not a problem).

- If I'm still getting the lean-code after, I'm going to take to a muffler shop and have the exhaust checked, to include the O2 sensors, if they can do it.

That's where I'm at right now - not 100%. But it runs!!! <img src="/forums/images/graemlins/kewl.gif" alt="" />