My 300se will start easily and run well for the first two or three minutes. Then (if in park) the vacuum gauge (economy) pegs almost to the right and the idle drops to almost stall and it runs rough. If driving during this period it acts as if starving for gas and has a top speed of 45mph. After a few minutes the gauge goes back to no vacuum and the car then runs smooth except it idles at 1500 rpm in park and 800 rpm in park. I have changed the plugs, fuel filter, cleaned the ICU, and replaced all leaking vacuum lines. Does anyone know what I should try next?