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Hi, I am having trouble identifying a problem with my 2003 Grand Voyager 3.3 Petrol Auto (EGA engine). Ever since an overheated engine caused a head gasket to blow 2 years ago - (Heads removed, skimmed and replaced). The symptoms I have are an occasional rough idle when stationary. It is just slightly annoying and tends to happen when you stop in traffic with the transmission in Drive.It used to be that it happened about 30% of the time when stopped, but now it is nearly 90% of the time. Turning off the A/C and shifting to Neutral alleviates the slight body shake caused by the rough idle. Once the vehicle is moving though everything is fine, good acceleration, smooth, normal fuel consumption etc. I get no OBD error codes. When idling and hot, with a hand over the exhast, you can feel the occasional miss from the rough idle. When engine is cold, idle is OK I have taken most of the steps that I would consider normal to fix a rough idle which would focus on things that cause a bad burn at idle. So, I have replaced (with new) Spark Plugs, HT Leads, Coil Pack, IAT Sensor, MAP Sensor, CMP Sensor, PCV Valve, Upstream and Downstream O2 Sensors. I have also replaced the upper intake manifold, resealed lower intake manifold, changed throttle body with Idle Air control valve and throttle position sensor with second user replacement parts. I have also tried gas testing the air intake areas with no change in engine idle. I have clamped/isolated the EVAP cannister and Crankcase vent hoses etc and checked their continuity. I have checked all cylinder compressions and although they vary they are within the manuals range of upper and lower. Nothing changes the idle symptoms. I have a Launch CR123, to analyse the PCM. I can see the switching of the Upstream Sensor, Downstream seems to stay in the middle. The O2 test which is an option on the analyser does not work on the vehicle. There is an option with the scanner to check live data streams. These all check out OK ie pass, except $17 live data stream which registers a fail. I cannot find anything that tells me what this is. I would be grateful if anyone has any info on the $17 data stream or anything else that could be suggested to help me stop this rough idle. My next steps are to replace the lower intake manifold, change the o2 sensors again, replace the cat. I have assumed that all the new parts I have are OK but am thinking they may not be. I am beginning to run out of ideas and would welcome some thoughtful assistance. Many Thanks...