Q: Engine Running Rough, EGR or TPS?

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Background info: We swapped in a used (98k) VG33E V6 when the factory VG33E V6 seized at (184k). We just got to the stage of getting it running but we can't seem to get it to run correctly.

My idle is high, about 1,400 RPMS give or take. Idles smooth but when put into gear and with no acceleration is sputters. It accelerates without my foot even on the gas, although not quickly but for example if I get to about 25mph it will continue at that speed for the most part. Not un-operable, but still an issue. It accelerates very slowly. It almost seems like it just doesn't want to go into gear or that the computer doesn't recognize how much I'm trying to accelerate. Even when I put the petal to the floor it takes a second for it to register and even then it only seems like the RPMs raise but the actual acceleration doesn't. So far I have tried to adjust the TPS sensor (has been replaced), the distributor (has been replaced), and the IAC Valve (has been replaced). I have ran codes using an INNOVA 3100 OBD2 scan tool and I was getting an EGR code but that seems to have cleared up and was left with is random misfires. However, the EGR code has just reappeared (P0400) and the random misfires code is gone. I'm not mechanically inclined but I've had my mechanic father (american cars/heavy machinery) help me out and he is even stumped by this. I also wouldn't think that the timing would have to do with these issues other than the backfire noise I get sometimes.

My car has 98000 miles.
My car has an automatic transmission.

Hi there. Swapping out motors today is much more complex than in years past due to the electronics and computer controlled or monitored systems. The issue you’re describing is a common symptom with engine swaps like the one you’ve recently completed; and even professional automotive mechanics are often baffled by the root cause. In some instances it’s related to a connectivity error with the ignition system; either a faulty electrical harness to fuel injectors or the throttle position sensor itself is faulty. It could be as simple as a vacuum leak as well. I wish we could offer more advice, but without being there to inspect the vehicle personally, there really isn’t an easy fix to this solution.

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