Slight surging, already did all of the normal stuff

[desertpierat]

New wires & plugs, used coils and ICM, and new cat. Bad coils/ICM from the yard? Other ideas?

[MKMike]

Fuel pressure/fuel delivery issues, perhaps?

Assuming there are no codes--hook up a fuel pressure gauge.

Take the following 3 readings and write them down
A) Read fuel pressure Key On /engine OFF (KOEO) should be above 50
B)Key On /engine running (KOER ) mid to upper 40's is typical running fuel pressure
C)Key on/ engine running -- disconnect vacuum hose to fuel pressure regulator and then reconnect it
When you do this there should be approximately a 10 psi increase in fuel pressure until the vacuum hose is reconnected.
If pressure does not increase, you have a faulty FPR.
There should not be any gasoline in the FPR vacuum hose.

Service manual lists normal fuel pressures as:
2000 - 2004 VIN 1 & K KOEO 53-59 psi
2000 - 2004 VIN 1 & K KOER 3-10 psi less than above BUT not below 48 psi

FSM also states that pressures below 48PSI are known to cause issues.

[desertpierat]

I'll get a fuel pressure gauge this week and check it out. I should add the only time I notice this is in 4th going straight. No issues going WOT, starting, idling, or anything else.