Cause of my issues - J30 motor

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After some tech help from Z1Motorsports, came to the realization that the motor in my 90 300zx NA has been swapped with one from a J30. I've already replaced the FPR, fuel filter, lower radiator hose, plugs (NGK PFR6B-11) & oil filter. Is any of this going to be replaced with the J30 components?

[DCaff300ZX]

To my knowledge the two engines are the same and so those parts should be the same or wouldn't install and run, although the part numbers would be different.
Your question was hard to determine, do you mean that you now have the swapped J30 engine and you had added the mentioned parts to your NA motor previously, and want to now use them on the J30 if possible?

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I put the 300zx parts on, not knowing that it was a j30 motor until I couldn't figure out why I couldn't find an upper radiator hose to fit it. Bottom hose fit good, but I guess the water outlet neck is a few inches shorter. Ended up having to use a j30 hose & cut it to fit. But I used the 300 plugs.

It seems to run fine, but I'm still dropping rpms & stumbling occasionally at red lights.