Got code e-49...cleaned throttle body and checked the hoses from the egr valves no leaks. car ran good for two months. now the problem is back.checked codes and e-49 came up again. I cleared the codes and got0.9.0 then 7.0..now when I drive it seems like I have the cruise control on. it will hold the speed of 30mph and i don't even have my foot on the gas. should i replace the diverter valve and the egr valve?
why is my 1990 deville idling high at start up and then idling itself down after on 1990 Cadillac DeVille
idle control motor is a common failure for the 4.9. you should have it checked at a shop and i would not throw any parts at it till you know the exact failure.