I'd second that advice. Try spraying some 'quick start' (volatile, but safe if there is no open flame or red-hot metal) around the vacuum lines/connections at idle. A leak will bring the idle up as the stuff enriches the mixture in the incoming air-stream. There is a large rubber plenum under the air cleaner which is prone to cracking. I fixed mine with silicone, for now, and plan a tear-down to replace it next winter. You need to get a paper copy of the 117 or 116 engine manual, or the CD, and read up. Most of the vacuum diagrams won't help to find leaks anyway, but will aid in understanding functionality. Welcome to the forum too...

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1986 560SL
2002 Toyota Camry
1993 Lexus