All of a sudden I've been experiencing random loss of power accompanied by engine shake. It seems like the engine is misfiring. I replaced the plugs with NGK's a couple months back as well as the wires with MSD 8mm. The opti was changed almost 3yrs ago, but has less than 15k miles on it. I've already double checked for burnt wires and can't find any. The problem seems to occur under slight acceleration. I'm not sure if I'm imagining it, but the symptoms seem exaggerated when accelerating up hill. I took a run up to the store and logged it using free scan. If anyone can help me diagnose this I would very much appreciate it. Thanks =)

Here is my data log in Excel 2007 format. run3.xlsx

 

At idle, the long term fuel corrections (LTFT's) are bottomed out, pulling out the maximum possible amount of fuel (15%), to correct a rich condition. The LTFT's in the other cells are pulling out fuel as well, although generally not the maximum possible amount.

You have to determine whether this is a true rich condition, or a "false" rich condition.

 

I believe it is an actual rich condition. There is a stronger than usual smell of fuel in the exhaust and a fair amount of carbon build up too. The egr valve and pipe was removed recently and two Jegs block off plates were put in their place. I didn't reset the PCM after this. Do you think that could be the problem? I'll reset it today just to check. I'll get a second read after I drive awhile and the BLM's re-learn. What else could cause this?

 

Check for a vacuum or exhaust leak causing it. Don't overlook the intake possibly not sealing to the heads, loose intake bolts, etc.