likely be best to get a 2002 3800 engine harness, then of course you'll need a pcm to run it in a 02 with a l67.

grab a tb and maf from a 02. or in the canned tune you need have it changed to a 98 maf file. take your map sensor off the 98 and swap the pig tail if you end up with a na harness vs a sc harness.

your car dont have magna steer so its never gonna work in the 02 car.