Check the timing. My v6 has a rough idle too. I cleaned the lambda's - No change. replaced the spark plugs - No change, cleaned the throttle body - No change, compression test - Perfect
Doing the timing belt job I found that both rear bank cam's were out. The exhaust by a little, the inlet by a lot. You don't really need camlocks to check but you do neet a TDC guage. The cams have a very fine groove at the end. Set the engine to TDC on the compression stroke (so the inlet cam on the rear bank is pointing to approx 10 o'clock, you MUST set tdc by the crank though). Place a thin feeler gauge flat on the casting on the cylinder head and slide toward the camshaft. It should meet a tiny slot in the cam.
The cam position sensor is on the rear exhaust cam so if that one is out (and it often is) then it can cause idle problems.
You must compression test the rear bank as 9/10 this is where you will find poor compression.
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