Troubleshooting without a DTC is very challenging and is speculative, at best!

I think we all agreed that the "sluggish" problem suggests that you're experiencing Air/Fuel ratio issues. The LS430's ECM (Engine Control Module) controls the A/F ratio based primarily on inputs from IAT (Intake Air Temperature) sensor, MAF (Mass Air Flow) meter, and ECT (Engine Coolant Temperature) sensor. So when you step on the accelerator to add gas, the ECM controls the proper amount of air the engine will need according to inputs from these sensors.

Typically, a bad sensor will give you some error codes: MAF (P0100, P0101, P0102 and P0103); IAT (P0110, P0112, and P0113); ECT (P0115, P0116, P0117 and P0118). It's very possible that one or more failing sensors which are giving false readings but not "bad" enough to trigger any DTC; or you may have a failing ECM.

The IAT sensor is built-in in the MAF meter. There's not much that can go wrong with the MAF except maybe excessive buildup that requires cleaning once in a while.

The ECT sensor seems to be a maintenance item that yielded great result on restoring performance. Please take a look at the ECT sensor discussion HERE. If this were my car, I would start with replacing the ECT sensor.

Finally, let's hope that your ECM is not a culprit - replacing the ECM is a much bigger effort.

 

Hi dude i am having the same issue with my 01 430 , was your problem solved and if so how please tell me so i could try that