i found when the egr is unplugged it goes away, has a low rpm misfire, well i replaced the egr valve, dpfe sensor. and egr vacume solenoid. same problem. also a full tune up was done, fuel filter, plugs, coil packs everything. same problem. well i am reading 1.6 inch of vacume on the egr at idle which is normal. but i noticed with the egr plugged up and working my timing at idle is 16 or so and cruising its like 40-45 degrees of timing. it seems high, when i unplug the egr my timing drops to 30 or so and it runs fine. well i back probed the egr solenoid according to my troubleshooting steps and it say if you ground the egr solenoid and you get more than 4 in of vacume when you do this (at the egr) then you have a bad pcm, but the truck runs good with the egr unhooked, and i can communicate fine with everything. on a side note. the battery did go dead recently and i replaced it. could this be a computer relearn, or is this a bad pcm?

 

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