95 sc 400 idle speed in gear

[setaclay]

Hi, I have a 95 SC 400 with 34 K on it. I had the engine degreased ,what I dont know is, the engine warmed up idles about 550-600 in neutral, in gear down to 400, and i feel some vibration in the sterring wheel from a rough idle. I brought it in to Lexus and they said start by cleaning the thottle body, if that does not work, replace the motor, or ECu, this is expensive stuff, has anyone had this problem?

Thank you

Tony