Joe,
Sorry for the delay getting back to you. Problem is solved.
I decided to go to my independent MB/Porche shop and he found a little corrosion on one of the spark plug connections, but no water in the tubes. After a cleaning all the connections, he couldn't solve the idle problem and trac/check engine flashes. He suggested changing the wires, dist. cap, and rotors for a $415 bill.
I checked the service work done at the Lexus dealer since I bought the car at 70k mi. and they'd never changed those items, only the spark plugs (100k type). After the shock of the $800 estimate from Lexus, I decided to try the independent shop (Greff Auto.) for a while. I agreed to Greff's charges and it did solve the problem.
Certainly, it was ONE of the 3 things replaced that fixed it. I felt that because of the component's age and my mechanic's hourly rate, I was tired of playing troubleshooter and wanted it done. Now I know those items are solid. The engine compartment was dirty b/c I work at a yard with a lot of dust and regular rain which must splash around the engine compartment eventually. We hadn't cleaned it since buying it 3 years ago. We won't be cleaning it again anytime soon (and this time with a cloth, no hose!)
Thanks for your help.
Jimmy